/*
 * Copyright (C) 2014 Red Hat
 * Copyright (C) 2014 Intel Corp.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * Authors:
 * Rob Clark <robdclark@gmail.com>
 * Daniel Vetter <daniel.vetter@ffwll.ch>
 */

#include <drm/drmP.h>
#include <drm/drm_atomic.h>
#include <drm/drm_plane_helper.h>
#include <drm/drm_crtc_helper.h>
#include <drm/drm_atomic_helper.h>
#include <linux/fence.h>

/**
 * DOC: overview
 *
 * This helper library provides implementations of check and commit functions on
 * top of the CRTC modeset helper callbacks and the plane helper callbacks. It
 * also provides convenience implementations for the atomic state handling
 * callbacks for drivers which don't need to subclass the drm core structures to
 * add their own additional internal state.
 *
 * This library also provides default implementations for the check callback in
 * drm_atomic_helper_check and for the commit callback with
 * drm_atomic_helper_commit. But the individual stages and callbacks are expose
 * to allow drivers to mix and match and e.g. use the plane helpers only
 * together with a driver private modeset implementation.
 *
 * This library also provides implementations for all the legacy driver
 * interfaces on top of the atomic interface. See drm_atomic_helper_set_config,
 * drm_atomic_helper_disable_plane, drm_atomic_helper_disable_plane and the
 * various functions to implement set_property callbacks. New drivers must not
 * implement these functions themselves but must use the provided helpers.
 */
static void
drm_atomic_helper_plane_changed(struct drm_atomic_state *state,
                                struct drm_plane_state *plane_state,
                                struct drm_plane *plane)
{
        struct drm_crtc_state *crtc_state;

        if (plane->state->crtc) {
                crtc_state = state->crtc_states[drm_crtc_index(plane->state->crtc)];

                if (WARN_ON(!crtc_state))
                        return;

                crtc_state->planes_changed = true;
        }

        if (plane_state->crtc) {
                crtc_state =
                        state->crtc_states[drm_crtc_index(plane_state->crtc)];

                if (WARN_ON(!crtc_state))
                        return;

                crtc_state->planes_changed = true;
        }
}

static struct drm_crtc *
get_current_crtc_for_encoder(struct drm_device *dev,
                             struct drm_encoder *encoder)
{
        struct drm_mode_config *config = &dev->mode_config;
        struct drm_connector *connector;

        WARN_ON(!drm_modeset_is_locked(&config->connection_mutex));

        list_for_each_entry(connector, &config->connector_list, head) {
                if (connector->state->best_encoder != encoder)
                        continue;

                return connector->state->crtc;
        }

        return NULL;
}

static int
steal_encoder(struct drm_atomic_state *state,
              struct drm_encoder *encoder,
              struct drm_crtc *encoder_crtc)
{
        struct drm_mode_config *config = &state->dev->mode_config;
        struct drm_crtc_state *crtc_state;
        struct drm_connector *connector;
        struct drm_connector_state *connector_state;
        int ret;

        /*
         * We can only steal an encoder coming from a connector, which means we
         * must already hold the connection_mutex.
         */
        WARN_ON(!drm_modeset_is_locked(&config->connection_mutex));

        DRM_DEBUG_ATOMIC("[ENCODER:%d:%s] in use on [CRTC:%d], stealing it\n",
                         encoder->base.id, encoder->name,
                         encoder_crtc->base.id);

        crtc_state = drm_atomic_get_crtc_state(state, encoder_crtc);
        if (IS_ERR(crtc_state))
                return PTR_ERR(crtc_state);

        crtc_state->mode_changed = true;

        list_for_each_entry(connector, &config->connector_list, head) {
                if (connector->state->best_encoder != encoder)
                        continue;

                DRM_DEBUG_ATOMIC("Stealing encoder from [CONNECTOR:%d:%s]\n",
                                 connector->base.id,
                                 connector->name);

                connector_state = drm_atomic_get_connector_state(state,
                                                                 connector);
                if (IS_ERR(connector_state))
                        return PTR_ERR(connector_state);

                ret = drm_atomic_set_crtc_for_connector(connector_state, NULL);
                if (ret)
                        return ret;
                connector_state->best_encoder = NULL;
        }

        return 0;
}

static int
update_connector_routing(struct drm_atomic_state *state, int conn_idx)
{
        const struct drm_connector_helper_funcs *funcs;
        struct drm_encoder *new_encoder;
        struct drm_crtc *encoder_crtc;
        struct drm_connector *connector;
        struct drm_connector_state *connector_state;
        struct drm_crtc_state *crtc_state;
        int idx, ret;

        connector = state->connectors[conn_idx];
        connector_state = state->connector_states[conn_idx];

        if (!connector)
                return 0;

        DRM_DEBUG_ATOMIC("Updating routing for [CONNECTOR:%d:%s]\n",
                         connector->base.id,
                         connector->name);

        if (connector->state->crtc != connector_state->crtc) {
                if (connector->state->crtc) {
                        idx = drm_crtc_index(connector->state->crtc);

                        crtc_state = state->crtc_states[idx];
                        crtc_state->mode_changed = true;
                }

                if (connector_state->crtc) {
                        idx = drm_crtc_index(connector_state->crtc);

                        crtc_state = state->crtc_states[idx];
                        crtc_state->mode_changed = true;
                }
        }

        if (!connector_state->crtc) {
                DRM_DEBUG_ATOMIC("Disabling [CONNECTOR:%d:%s]\n",
                                connector->base.id,
                                connector->name);

                connector_state->best_encoder = NULL;

                return 0;
        }

        funcs = connector->helper_private;
        new_encoder = funcs->best_encoder(connector);

        if (!new_encoder) {
                DRM_DEBUG_ATOMIC("No suitable encoder found for [CONNECTOR:%d:%s]\n",
                                 connector->base.id,
                                 connector->name);
                return -EINVAL;
        }

        if (new_encoder == connector_state->best_encoder) {
                DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] keeps [ENCODER:%d:%s], now on [CRTC:%d]\n",
                                 connector->base.id,
                                 connector->name,
                                 new_encoder->base.id,
                                 new_encoder->name,
                                 connector_state->crtc->base.id);

                return 0;
        }

        encoder_crtc = get_current_crtc_for_encoder(state->dev,
                                                    new_encoder);

        if (encoder_crtc) {
                ret = steal_encoder(state, new_encoder, encoder_crtc);
                if (ret) {
                        DRM_DEBUG_ATOMIC("Encoder stealing failed for [CONNECTOR:%d:%s]\n",
                                         connector->base.id,
                                         connector->name);
                        return ret;
                }
        }

        connector_state->best_encoder = new_encoder;
        idx = drm_crtc_index(connector_state->crtc);

        crtc_state = state->crtc_states[idx];
        crtc_state->mode_changed = true;

        DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] using [ENCODER:%d:%s] on [CRTC:%d]\n",
                         connector->base.id,
                         connector->name,
                         new_encoder->base.id,
                         new_encoder->name,
                         connector_state->crtc->base.id);

        return 0;
}

static int
mode_fixup(struct drm_atomic_state *state)
{
        struct drm_crtc *crtc;
        struct drm_crtc_state *crtc_state;
        struct drm_connector *connector;
        struct drm_connector_state *conn_state;
        int i;
        bool ret;

        for_each_crtc_in_state(state, crtc, crtc_state, i) {
                if (!crtc_state->mode_changed)
                        continue;

                drm_mode_copy(&crtc_state->adjusted_mode, &crtc_state->mode);
        }

        for_each_connector_in_state(state, connector, conn_state, i) {
                const struct drm_encoder_helper_funcs *funcs;
                struct drm_encoder *encoder;

                WARN_ON(!!conn_state->best_encoder != !!conn_state->crtc);

                if (!conn_state->crtc || !conn_state->best_encoder)
                        continue;

                crtc_state =
                        state->crtc_states[drm_crtc_index(conn_state->crtc)];

                /*
                 * Each encoder has at most one connector (since we always steal
                 * it away), so we won't call ->mode_fixup twice.
                 */
                encoder = conn_state->best_encoder;
                funcs = encoder->helper_private;

                if (encoder->bridge && encoder->bridge->funcs->mode_fixup) {
                        ret = encoder->bridge->funcs->mode_fixup(
                                        encoder->bridge, &crtc_state->mode,
                                        &crtc_state->adjusted_mode);
                        if (!ret) {
                                DRM_DEBUG_ATOMIC("Bridge fixup failed\n");
                                return -EINVAL;
                        }
                }

                if (funcs->atomic_check) {
                        ret = funcs->atomic_check(encoder, crtc_state,
                                                  conn_state);
                        if (ret) {
                                DRM_DEBUG_ATOMIC("[ENCODER:%d:%s] check failed\n",
                                                 encoder->base.id, encoder->name);
                                return ret;
                        }
                } else {
                        ret = funcs->mode_fixup(encoder, &crtc_state->mode,
                                                &crtc_state->adjusted_mode);
                        if (!ret) {
                                DRM_DEBUG_ATOMIC("[ENCODER:%d:%s] fixup failed\n",
                                                 encoder->base.id, encoder->name);
                                return -EINVAL;
                        }
                }
        }

        for_each_crtc_in_state(state, crtc, crtc_state, i) {
                const struct drm_crtc_helper_funcs *funcs;

                if (!crtc_state->mode_changed)
                        continue;

                funcs = crtc->helper_private;
                ret = funcs->mode_fixup(crtc, &crtc_state->mode,
                                        &crtc_state->adjusted_mode);
                if (!ret) {
                        DRM_DEBUG_ATOMIC("[CRTC:%d] fixup failed\n",
                                         crtc->base.id);
                        return -EINVAL;
                }
        }

        return 0;
}

static bool
needs_modeset(struct drm_crtc_state *state)
{
        return state->mode_changed || state->active_changed;
}

/**
 * drm_atomic_helper_check_modeset - validate state object for modeset changes
 * @dev: DRM device
 * @state: the driver state object
 *
 * Check the state object to see if the requested state is physically possible.
 * This does all the crtc and connector related computations for an atomic
 * update. It computes and updates crtc_state->mode_changed, adds any additional
 * connectors needed for full modesets and calls down into ->mode_fixup
 * functions of the driver backend.
 *
 * IMPORTANT:
 *
 * Drivers which update ->mode_changed (e.g. in their ->atomic_check hooks if a
 * plane update can't be done without a full modeset) _must_ call this function
 * afterwards after that change. It is permitted to call this function multiple
 * times for the same update, e.g. when the ->atomic_check functions depend upon
 * the adjusted dotclock for fifo space allocation and watermark computation.
 *
 * RETURNS
 * Zero for success or -errno
 */
int
drm_atomic_helper_check_modeset(struct drm_device *dev,
                                struct drm_atomic_state *state)
{
        struct drm_crtc *crtc;
        struct drm_crtc_state *crtc_state;
        struct drm_connector *connector;
        struct drm_connector_state *connector_state;
        int i, ret;

        for_each_crtc_in_state(state, crtc, crtc_state, i) {
                if (!drm_mode_equal(&crtc->state->mode, &crtc_state->mode)) {
                        DRM_DEBUG_ATOMIC("[CRTC:%d] mode changed\n",
                                         crtc->base.id);
                        crtc_state->mode_changed = true;
                }

                if (crtc->state->enable != crtc_state->enable) {
                        DRM_DEBUG_ATOMIC("[CRTC:%d] enable changed\n",
                                         crtc->base.id);
                        crtc_state->mode_changed = true;
                }
        }

        for_each_connector_in_state(state, connector, connector_state, i) {
                /*
                 * This only sets crtc->mode_changed for routing changes,
                 * drivers must set crtc->mode_changed themselves when connector
                 * properties need to be updated.
                 */
                ret = update_connector_routing(state, i);
                if (ret)
                        return ret;
        }

        /*
         * After all the routing has been prepared we need to add in any
         * connector which is itself unchanged, but who's crtc changes it's
         * configuration. This must be done before calling mode_fixup in case a
         * crtc only changed its mode but has the same set of connectors.
         */
        for_each_crtc_in_state(state, crtc, crtc_state, i) {
                int num_connectors;

                /*
                 * We must set ->active_changed after walking connectors for
                 * otherwise an update that only changes active would result in
                 * a full modeset because update_connector_routing force that.
                 */
                if (crtc->state->active != crtc_state->active) {
                        DRM_DEBUG_ATOMIC("[CRTC:%d] active changed\n",
                                         crtc->base.id);
                        crtc_state->active_changed = true;
                }

                if (!needs_modeset(crtc_state))
                        continue;

                DRM_DEBUG_ATOMIC("[CRTC:%d] needs all connectors, enable: %c, active: %c\n",
                                 crtc->base.id,
                                 crtc_state->enable ? 'y' : 'n',
                              crtc_state->active ? 'y' : 'n');

                ret = drm_atomic_add_affected_connectors(state, crtc);
                if (ret != 0)
                        return ret;

                num_connectors = drm_atomic_connectors_for_crtc(state,
                                                                crtc);

                if (crtc_state->enable != !!num_connectors) {
                        DRM_DEBUG_ATOMIC("[CRTC:%d] enabled/connectors mismatch\n",
                                         crtc->base.id);

                        return -EINVAL;
                }
        }

        return mode_fixup(state);
}
EXPORT_SYMBOL(drm_atomic_helper_check_modeset);

/**
 * drm_atomic_helper_check_planes - validate state object for planes changes
 * @dev: DRM device
 * @state: the driver state object
 *
 * Check the state object to see if the requested state is physically possible.
 * This does all the plane update related checks using by calling into the
 * ->atomic_check hooks provided by the driver.
 *
 * RETURNS
 * Zero for success or -errno
 */
int
drm_atomic_helper_check_planes(struct drm_device *dev,
                               struct drm_atomic_state *state)
{
        struct drm_crtc *crtc;
        struct drm_crtc_state *crtc_state;
        struct drm_plane *plane;
        struct drm_plane_state *plane_state;
        int i, ret = 0;

        for_each_plane_in_state(state, plane, plane_state, i) {
                const struct drm_plane_helper_funcs *funcs;

                funcs = plane->helper_private;

                drm_atomic_helper_plane_changed(state, plane_state, plane);

                if (!funcs || !funcs->atomic_check)
                        continue;

                ret = funcs->atomic_check(plane, plane_state);
                if (ret) {
                        DRM_DEBUG_ATOMIC("[PLANE:%d] atomic driver check failed\n",
                                         plane->base.id);
                        return ret;
                }
        }

        for_each_crtc_in_state(state, crtc, crtc_state, i) {
                const struct drm_crtc_helper_funcs *funcs;

                funcs = crtc->helper_private;

                if (!funcs || !funcs->atomic_check)
                        continue;

                ret = funcs->atomic_check(crtc, state->crtc_states[i]);
                if (ret) {
                        DRM_DEBUG_ATOMIC("[CRTC:%d] atomic driver check failed\n",
                                         crtc->base.id);
                        return ret;
                }
        }

        return ret;
}
EXPORT_SYMBOL(drm_atomic_helper_check_planes);

/**
 * drm_atomic_helper_check - validate state object
 * @dev: DRM device
 * @state: the driver state object
 *
 * Check the state object to see if the requested state is physically possible.
 * Only crtcs and planes have check callbacks, so for any additional (global)
 * checking that a driver needs it can simply wrap that around this function.
 * Drivers without such needs can directly use this as their ->atomic_check()
 * callback.
 *
 * This just wraps the two parts of the state checking for planes and modeset
 * state in the default order: First it calls drm_atomic_helper_check_modeset()
 * and then drm_atomic_helper_check_planes(). The assumption is that the
 * ->atomic_check functions depend upon an updated adjusted_mode.clock to
 * e.g. properly compute watermarks.
 *
 * RETURNS
 * Zero for success or -errno
 */
int drm_atomic_helper_check(struct drm_device *dev,
                            struct drm_atomic_state *state)
{
        int ret;

        ret = drm_atomic_helper_check_modeset(dev, state);
        if (ret)
                return ret;

        ret = drm_atomic_helper_check_planes(dev, state);
        if (ret)
                return ret;

        return ret;
}
EXPORT_SYMBOL(drm_atomic_helper_check);

static void
disable_outputs(struct drm_device *dev, struct drm_atomic_state *old_state)
{
        struct drm_connector *connector;
        struct drm_connector_state *old_conn_state;
        struct drm_crtc *crtc;
        struct drm_crtc_state *old_crtc_state;
        int i;

        for_each_connector_in_state(old_state, connector, old_conn_state, i) {
                const struct drm_encoder_helper_funcs *funcs;
                struct drm_encoder *encoder;
                struct drm_crtc_state *old_crtc_state;

                /* Shut down everything that's in the changeset and currently
                 * still on. So need to check the old, saved state. */
                if (!old_conn_state->crtc)
                        continue;

                old_crtc_state = old_state->crtc_states[drm_crtc_index(old_conn_state->crtc)];

                if (!old_crtc_state->active ||
                    !needs_modeset(old_conn_state->crtc->state))
                        continue;

                encoder = old_conn_state->best_encoder;

                /* We shouldn't get this far if we didn't previously have
                 * an encoder.. but WARN_ON() rather than explode.
                 */
                if (WARN_ON(!encoder))
                        continue;

                funcs = encoder->helper_private;

                DRM_DEBUG_ATOMIC("disabling [ENCODER:%d:%s]\n",
                                 encoder->base.id, encoder->name);

                /*
                 * Each encoder has at most one connector (since we always steal
                 * it away), so we won't call disable hooks twice.
                 */
                if (encoder->bridge)
                        encoder->bridge->funcs->disable(encoder->bridge);

                /* Right function depends upon target state. */
                if (connector->state->crtc && funcs->prepare)
                        funcs->prepare(encoder);
                else if (funcs->disable)
                        funcs->disable(encoder);
                else
                        funcs->dpms(encoder, DRM_MODE_DPMS_OFF);

                if (encoder->bridge)
                        encoder->bridge->funcs->post_disable(encoder->bridge);
        }

        for_each_crtc_in_state(old_state, crtc, old_crtc_state, i) {
                const struct drm_crtc_helper_funcs *funcs;

                /* Shut down everything that needs a full modeset. */
                if (!needs_modeset(crtc->state))
                        continue;

                if (!old_crtc_state->active)
                        continue;

                funcs = crtc->helper_private;

                DRM_DEBUG_ATOMIC("disabling [CRTC:%d]\n",
                                 crtc->base.id);


                /* Right function depends upon target state. */
                if (crtc->state->enable && funcs->prepare)
                        funcs->prepare(crtc);
                else if (funcs->disable)
                        funcs->disable(crtc);
                else
                        funcs->dpms(crtc, DRM_MODE_DPMS_OFF);
        }
}

static void
set_routing_links(struct drm_device *dev, struct drm_atomic_state *old_state)
{
        struct drm_connector *connector;
        struct drm_connector_state *old_conn_state;
        struct drm_crtc *crtc;
        struct drm_crtc_state *old_crtc_state;
        int i;

        /* clear out existing links */
        for_each_connector_in_state(old_state, connector, old_conn_state, i) {
                if (!connector->encoder)
                        continue;

                WARN_ON(!connector->encoder->crtc);

                connector->encoder->crtc = NULL;
                connector->encoder = NULL;
        }

        /* set new links */
        for_each_connector_in_state(old_state, connector, old_conn_state, i) {
                if (!connector->state->crtc)
                        continue;

                if (WARN_ON(!connector->state->best_encoder))
                        continue;

                connector->encoder = connector->state->best_encoder;
                connector->encoder->crtc = connector->state->crtc;
        }

        /* set legacy state in the crtc structure */
        for_each_crtc_in_state(old_state, crtc, old_crtc_state, i) {
                crtc->mode = crtc->state->mode;
                crtc->enabled = crtc->state->enable;
                crtc->x = crtc->primary->state->src_x >> 16;
                crtc->y = crtc->primary->state->src_y >> 16;
        }
}

static void
crtc_set_mode(struct drm_device *dev, struct drm_atomic_state *old_state)
{
        struct drm_crtc *crtc;
        struct drm_crtc_state *old_crtc_state;
        struct drm_connector *connector;
        struct drm_connector_state *old_conn_state;
        int i;

        for_each_crtc_in_state(old_state, crtc, old_crtc_state, i) {
                const struct drm_crtc_helper_funcs *funcs;

                if (!crtc->state->mode_changed)
                        continue;

                funcs = crtc->helper_private;

                if (crtc->state->enable && funcs->mode_set_nofb) {
                        DRM_DEBUG_ATOMIC("modeset on [CRTC:%d]\n",
                                         crtc->base.id);

                        funcs->mode_set_nofb(crtc);
                }
        }

        for_each_connector_in_state(old_state, connector, old_conn_state, i) {
                const struct drm_encoder_helper_funcs *funcs;
                struct drm_crtc_state *new_crtc_state;
                struct drm_encoder *encoder;
                struct drm_display_mode *mode, *adjusted_mode;

                if (!connector->state->best_encoder)
                        continue;

                encoder = connector->state->best_encoder;
                funcs = encoder->helper_private;
                new_crtc_state = connector->state->crtc->state;
                mode = &new_crtc_state->mode;
                adjusted_mode = &new_crtc_state->adjusted_mode;

                if (!new_crtc_state->mode_changed)
                        continue;

                DRM_DEBUG_ATOMIC("modeset on [ENCODER:%d:%s]\n",
                                 encoder->base.id, encoder->name);

                /*
                 * Each encoder has at most one connector (since we always steal
                 * it away), so we won't call mode_set hooks twice.
                 */
                if (funcs->mode_set)
                        funcs->mode_set(encoder, mode, adjusted_mode);

                if (encoder->bridge && encoder->bridge->funcs->mode_set)
                        encoder->bridge->funcs->mode_set(encoder->bridge,
                                                         mode, adjusted_mode);
        }
}

/**
 * drm_atomic_helper_commit_modeset_disables - modeset commit to disable outputs
 * @dev: DRM device
 * @old_state: atomic state object with old state structures
 *
 * This function shuts down all the outputs that need to be shut down and
 * prepares them (if required) with the new mode.
 *
 * For compatability with legacy crtc helpers this should be called before
 * drm_atomic_helper_commit_planes(), which is what the default commit function
 * does. But drivers with different needs can group the modeset commits together
 * and do the plane commits at the end. This is useful for drivers doing runtime
 * PM since planes updates then only happen when the CRTC is actually enabled.
 */
void drm_atomic_helper_commit_modeset_disables(struct drm_device *dev,
                                               struct drm_atomic_state *old_state)
{
        disable_outputs(dev, old_state);
        set_routing_links(dev, old_state);
        crtc_set_mode(dev, old_state);
}
EXPORT_SYMBOL(drm_atomic_helper_commit_modeset_disables);

/**
 * drm_atomic_helper_commit_modeset_enables - modeset commit to enable outputs
 * @dev: DRM device
 * @old_state: atomic state object with old state structures
 *
 * This function enables all the outputs with the new configuration which had to
 * be turned off for the update.
 *
 * For compatability with legacy crtc helpers this should be called after
 * drm_atomic_helper_commit_planes(), which is what the default commit function
 * does. But drivers with different needs can group the modeset commits together
 * and do the plane commits at the end. This is useful for drivers doing runtime
 * PM since planes updates then only happen when the CRTC is actually enabled.
 */
void drm_atomic_helper_commit_modeset_enables(struct drm_device *dev,
                                              struct drm_atomic_state *old_state)
{
        struct drm_crtc *crtc;
        struct drm_crtc_state *old_crtc_state;
        struct drm_connector *connector;
        struct drm_connector_state *old_conn_state;
        int i;

        for_each_crtc_in_state(old_state, crtc, old_crtc_state, i) {
                const struct drm_crtc_helper_funcs *funcs;

                /* Need to filter out CRTCs where only planes change. */
                if (!needs_modeset(crtc->state))
                        continue;

                if (!crtc->state->active)
                        continue;

                funcs = crtc->helper_private;

                if (crtc->state->enable) {
                        DRM_DEBUG_ATOMIC("enabling [CRTC:%d]\n",
                                         crtc->base.id);

                        if (funcs->enable)
                                funcs->enable(crtc);
                        else
                                funcs->commit(crtc);
                }
        }

        for_each_connector_in_state(old_state, connector, old_conn_state, i) {
                const struct drm_encoder_helper_funcs *funcs;
                struct drm_encoder *encoder;

                if (!connector->state->best_encoder)
                        continue;

                if (!connector->state->crtc->state->active ||
                    !needs_modeset(connector->state->crtc->state))
                        continue;

                encoder = connector->state->best_encoder;
                funcs = encoder->helper_private;

                DRM_DEBUG_ATOMIC("enabling [ENCODER:%d:%s]\n",
                                 encoder->base.id, encoder->name);

                /*
                 * Each encoder has at most one connector (since we always steal
                 * it away), so we won't call enable hooks twice.
                 */
                if (encoder->bridge)
                        encoder->bridge->funcs->pre_enable(encoder->bridge);

                if (funcs->enable)
                        funcs->enable(encoder);
                else
                        funcs->commit(encoder);

                if (encoder->bridge)
                        encoder->bridge->funcs->enable(encoder->bridge);
        }
}
EXPORT_SYMBOL(drm_atomic_helper_commit_modeset_enables);

static void wait_for_fences(struct drm_device *dev,
                            struct drm_atomic_state *state)
{
        struct drm_plane *plane;
        struct drm_plane_state *plane_state;
        int i;

        for_each_plane_in_state(state, plane, plane_state, i) {
                if (!plane->state->fence)
                        continue;

                WARN_ON(!plane->state->fb);

                fence_wait(plane->state->fence, false);
                fence_put(plane->state->fence);
                plane->state->fence = NULL;
        }
}

static bool framebuffer_changed(struct drm_device *dev,
                                struct drm_atomic_state *old_state,
                                struct drm_crtc *crtc)
{
        struct drm_plane *plane;
        struct drm_plane_state *old_plane_state;
        int i;

        for_each_plane_in_state(old_state, plane, old_plane_state, i) {
                if (plane->state->crtc != crtc &&
                    old_plane_state->crtc != crtc)
                        continue;

                if (plane->state->fb != old_plane_state->fb)
                        return true;
        }

        return false;
}

/**
 * drm_atomic_helper_wait_for_vblanks - wait for vblank on crtcs
 * @dev: DRM device
 * @old_state: atomic state object with old state structures
 *
 * Helper to, after atomic commit, wait for vblanks on all effected
 * crtcs (ie. before cleaning up old framebuffers using
 * drm_atomic_helper_cleanup_planes()). It will only wait on crtcs where the
 * framebuffers have actually changed to optimize for the legacy cursor and
 * plane update use-case.
 */
void
drm_atomic_helper_wait_for_vblanks(struct drm_device *dev,
                struct drm_atomic_state *old_state)
{
        struct drm_crtc *crtc;
        struct drm_crtc_state *old_crtc_state;
        int i, ret;

        for_each_crtc_in_state(old_state, crtc, old_crtc_state, i) {
                /* No one cares about the old state, so abuse it for tracking
                 * and store whether we hold a vblank reference (and should do a
                 * vblank wait) in the ->enable boolean. */
                old_crtc_state->enable = false;

                if (!crtc->state->enable)
                        continue;

                /* Legacy cursor ioctls are completely unsynced, and userspace
                 * relies on that (by doing tons of cursor updates). */
                if (old_state->legacy_cursor_update)
                        continue;

                if (!framebuffer_changed(dev, old_state, crtc))
                        continue;

                ret = drm_crtc_vblank_get(crtc);
                if (ret != 0)
                        continue;

                old_crtc_state->enable = true;
                old_crtc_state->last_vblank_count = drm_vblank_count(dev, i);
        }

        for_each_crtc_in_state(old_state, crtc, old_crtc_state, i) {
                if (!old_crtc_state->enable)
                        continue;

                ret = wait_event_timeout(dev->vblank[i].queue,
                                old_crtc_state->last_vblank_count !=
                                        drm_vblank_count(dev, i),
                                msecs_to_jiffies(50));

                drm_crtc_vblank_put(crtc);
        }
}
EXPORT_SYMBOL(drm_atomic_helper_wait_for_vblanks);

/**
 * drm_atomic_helper_commit - commit validated state object
 * @dev: DRM device
 * @state: the driver state object
 * @async: asynchronous commit
 *
 * This function commits a with drm_atomic_helper_check() pre-validated state
 * object. This can still fail when e.g. the framebuffer reservation fails. For
 * now this doesn't implement asynchronous commits.
 *
 * RETURNS
 * Zero for success or -errno.
 */
int drm_atomic_helper_commit(struct drm_device *dev,
                             struct drm_atomic_state *state,
                             bool async)
{
        int ret;

        if (async)
                return -EBUSY;

        ret = drm_atomic_helper_prepare_planes(dev, state);
        if (ret)
                return ret;

        /*
         * This is the point of no return - everything below never fails except
         * when the hw goes bonghits. Which means we can commit the new state on
         * the software side now.
         */

        drm_atomic_helper_swap_state(dev, state);

        /*
         * Everything below can be run asynchronously without the need to grab
         * any modeset locks at all under one condition: It must be guaranteed
         * that the asynchronous work has either been cancelled (if the driver
         * supports it, which at least requires that the framebuffers get
         * cleaned up with drm_atomic_helper_cleanup_planes()) or completed
         * before the new state gets committed on the software side with
         * drm_atomic_helper_swap_state().
         *
         * This scheme allows new atomic state updates to be prepared and
         * checked in parallel to the asynchronous completion of the previous
         * update. Which is important since compositors need to figure out the
         * composition of the next frame right after having submitted the
         * current layout.
         */

        wait_for_fences(dev, state);

        drm_atomic_helper_commit_modeset_disables(dev, state);

        drm_atomic_helper_commit_planes(dev, state);

        drm_atomic_helper_commit_modeset_enables(dev, state);

        drm_atomic_helper_wait_for_vblanks(dev, state);

        drm_atomic_helper_cleanup_planes(dev, state);

        drm_atomic_state_free(state);

        return 0;
}
EXPORT_SYMBOL(drm_atomic_helper_commit);

/**
 * DOC: implementing async commit
 *
 * For now the atomic helpers don't support async commit directly. If there is
 * real need it could be added though, using the dma-buf fence infrastructure
 * for generic synchronization with outstanding rendering.
 *
 * For now drivers have to implement async commit themselves, with the following
 * sequence being the recommended one:
 *

 * 1. Run drm_atomic_helper_prepare_planes() first. This is the only function
 * which commit needs to call which can fail, so we want to run it first and
 * synchronously.
 *
 * 2. Synchronize with any outstanding asynchronous commit worker threads which
 * might be affected the new state update. This can be done by either cancelling
 * or flushing the work items, depending upon whether the driver can deal with
 * cancelled updates. Note that it is important to ensure that the framebuffer
 * cleanup is still done when cancelling.
 *
 * For sufficient parallelism it is recommended to have a work item per crtc
 * (for updates which don't touch global state) and a global one. Then we only
 * need to synchronize with the crtc work items for changed crtcs and the global
 * work item, which allows nice concurrent updates on disjoint sets of crtcs.
 *
 * 3. The software state is updated synchronously with
 * drm_atomic_helper_swap_state. Doing this under the protection of all modeset
 * locks means concurrent callers never see inconsistent state. And doing this
 * while it's guaranteed that no relevant async worker runs means that async
 * workers do not need grab any locks. Actually they must not grab locks, for
 * otherwise the work flushing will deadlock.
 *
 * 4. Schedule a work item to do all subsequent steps, using the split-out
 * commit helpers: a) pre-plane commit b) plane commit c) post-plane commit and
 * then cleaning up the framebuffers after the old framebuffer is no longer
 * being displayed.
 */

/**
 * drm_atomic_helper_prepare_planes - prepare plane resources before commit
 * @dev: DRM device
 * @state: atomic state object with new state structures
 *
 * This function prepares plane state, specifically framebuffers, for the new
 * configuration. If any failure is encountered this function will call
 * ->cleanup_fb on any already successfully prepared framebuffer.
 *
 * Returns:
 * 0 on success, negative error code on failure.
 */
int drm_atomic_helper_prepare_planes(struct drm_device *dev,
                                     struct drm_atomic_state *state)
{
        int nplanes = dev->mode_config.num_total_plane;
        int ret, i;

        for (i = 0; i < nplanes; i++) {
                const struct drm_plane_helper_funcs *funcs;
                struct drm_plane *plane = state->planes[i];
                struct drm_plane_state *plane_state = state->plane_states[i];
                struct drm_framebuffer *fb;

                if (!plane)
                        continue;

                funcs = plane->helper_private;

                fb = plane_state->fb;

                if (fb && funcs->prepare_fb) {
                        ret = funcs->prepare_fb(plane, fb, plane_state);
                        if (ret)
                                goto fail;
                }
        }

        return 0;

fail:
        for (i--; i >= 0; i--) {
                const struct drm_plane_helper_funcs *funcs;
                struct drm_plane *plane = state->planes[i];
                struct drm_plane_state *plane_state = state->plane_states[i];
                struct drm_framebuffer *fb;

                if (!plane)
                        continue;

                funcs = plane->helper_private;

                fb = state->plane_states[i]->fb;

                if (fb && funcs->cleanup_fb)
                        funcs->cleanup_fb(plane, fb, plane_state);

        }

        return ret;
}
EXPORT_SYMBOL(drm_atomic_helper_prepare_planes);

/**
 * drm_atomic_helper_commit_planes - commit plane state
 * @dev: DRM device
 * @old_state: atomic state object with old state structures
 *
 * This function commits the new plane state using the plane and atomic helper
 * functions for planes and crtcs. It assumes that the atomic state has already
 * been pushed into the relevant object state pointers, since this step can no
 * longer fail.
 *
 * It still requires the global state object @old_state to know which planes and
 * crtcs need to be updated though.
 */
void drm_atomic_helper_commit_planes(struct drm_device *dev,
                                     struct drm_atomic_state *old_state)
{
        struct drm_crtc *crtc;
        struct drm_crtc_state *old_crtc_state;
        struct drm_plane *plane;
        struct drm_plane_state *old_plane_state;
        int i;

        for_each_crtc_in_state(old_state, crtc, old_crtc_state, i) {
                const struct drm_crtc_helper_funcs *funcs;

                funcs = crtc->helper_private;

                if (!funcs || !funcs->atomic_begin)
                        continue;

                funcs->atomic_begin(crtc);
        }

        for_each_plane_in_state(old_state, plane, old_plane_state, i) {
                const struct drm_plane_helper_funcs *funcs;

                funcs = plane->helper_private;

                if (!funcs)
                        continue;

                old_plane_state = old_state->plane_states[i];

                /*
                 * Special-case disabling the plane if drivers support it.
                 */
                if (drm_atomic_plane_disabling(plane, old_plane_state) &&
                    funcs->atomic_disable)
                        funcs->atomic_disable(plane, old_plane_state);
                else
                        funcs->atomic_update(plane, old_plane_state);
        }

        for_each_crtc_in_state(old_state, crtc, old_crtc_state, i) {
                const struct drm_crtc_helper_funcs *funcs;

                funcs = crtc->helper_private;

                if (!funcs || !funcs->atomic_flush)
                        continue;

                funcs->atomic_flush(crtc);
        }
}
EXPORT_SYMBOL(drm_atomic_helper_commit_planes);

/**
 * drm_atomic_helper_cleanup_planes - cleanup plane resources after commit
 * @dev: DRM device
 * @old_state: atomic state object with old state structures
 *
 * This function cleans up plane state, specifically framebuffers, from the old
 * configuration. Hence the old configuration must be perserved in @old_state to
 * be able to call this function.
 *
 * This function must also be called on the new state when the atomic update
 * fails at any point after calling drm_atomic_helper_prepare_planes().
 */
void drm_atomic_helper_cleanup_planes(struct drm_device *dev,
                                      struct drm_atomic_state *old_state)
{
        struct drm_plane *plane;
        struct drm_plane_state *plane_state;
        int i;

        for_each_plane_in_state(old_state, plane, plane_state, i) {
                const struct drm_plane_helper_funcs *funcs;
                struct drm_framebuffer *old_fb;

                funcs = plane->helper_private;

                old_fb = plane_state->fb;

                if (old_fb && funcs->cleanup_fb)
                        funcs->cleanup_fb(plane, old_fb, plane_state);
        }
}
EXPORT_SYMBOL(drm_atomic_helper_cleanup_planes);

/**
 * drm_atomic_helper_swap_state - store atomic state into current sw state
 * @dev: DRM device
 * @state: atomic state
 *
 * This function stores the atomic state into the current state pointers in all
 * driver objects. It should be called after all failing steps have been done
 * and succeeded, but before the actual hardware state is committed.
 *
 * For cleanup and error recovery the current state for all changed objects will
 * be swaped into @state.
 *
 * With that sequence it fits perfectly into the plane prepare/cleanup sequence:
 *
 * 1. Call drm_atomic_helper_prepare_planes() with the staged atomic state.
 *
 * 2. Do any other steps that might fail.
 *
 * 3. Put the staged state into the current state pointers with this function.
 *
 * 4. Actually commit the hardware state.
 *
 * 5. Call drm_atomic_helper_cleanup_planes with @state, which since step 3
 * contains the old state. Also do any other cleanup required with that state.
 */
void drm_atomic_helper_swap_state(struct drm_device *dev,
                                  struct drm_atomic_state *state)
{
        int i;

        for (i = 0; i < dev->mode_config.num_connector; i++) {
                struct drm_connector *connector = state->connectors[i];

                if (!connector)
                        continue;

                connector->state->state = state;
                swap(state->connector_states[i], connector->state);
                connector->state->state = NULL;
        }

        for (i = 0; i < dev->mode_config.num_crtc; i++) {
                struct drm_crtc *crtc = state->crtcs[i];

                if (!crtc)
                        continue;

                crtc->state->state = state;
                swap(state->crtc_states[i], crtc->state);
                crtc->state->state = NULL;
        }

        for (i = 0; i < dev->mode_config.num_total_plane; i++) {
                struct drm_plane *plane = state->planes[i];

                if (!plane)
                        continue;

                plane->state->state = state;
                swap(state->plane_states[i], plane->state);
                plane->state->state = NULL;
        }
}
EXPORT_SYMBOL(drm_atomic_helper_swap_state);

/**
 * drm_atomic_helper_update_plane - Helper for primary plane update using atomic
 * @plane: plane object to update
 * @crtc: owning CRTC of owning plane
 * @fb: framebuffer to flip onto plane
 * @crtc_x: x offset of primary plane on crtc
 * @crtc_y: y offset of primary plane on crtc
 * @crtc_w: width of primary plane rectangle on crtc
 * @crtc_h: height of primary plane rectangle on crtc
 * @src_x: x offset of @fb for panning
 * @src_y: y offset of @fb for panning
 * @src_w: width of source rectangle in @fb
 * @src_h: height of source rectangle in @fb
 *
 * Provides a default plane update handler using the atomic driver interface.
 *
 * RETURNS:
 * Zero on success, error code on failure
 */
int drm_atomic_helper_update_plane(struct drm_plane *plane,
                                   struct drm_crtc *crtc,
                                   struct drm_framebuffer *fb,
                                   int crtc_x, int crtc_y,
                                   unsigned int crtc_w, unsigned int crtc_h,
                                   uint32_t src_x, uint32_t src_y,
                                   uint32_t src_w, uint32_t src_h)
{
        struct drm_atomic_state *state;
        struct drm_plane_state *plane_state;
        int ret = 0;

        state = drm_atomic_state_alloc(plane->dev);
        if (!state)
                return -ENOMEM;

        state->acquire_ctx = drm_modeset_legacy_acquire_ctx(crtc);
retry:
        plane_state = drm_atomic_get_plane_state(state, plane);
        if (IS_ERR(plane_state)) {
                ret = PTR_ERR(plane_state);
                goto fail;
        }

        ret = drm_atomic_set_crtc_for_plane(plane_state, crtc);
        if (ret != 0)
                goto fail;
        drm_atomic_set_fb_for_plane(plane_state, fb);
        plane_state->crtc_x = crtc_x;
        plane_state->crtc_y = crtc_y;
        plane_state->crtc_h = crtc_h;
        plane_state->crtc_w = crtc_w;
        plane_state->src_x = src_x;
        plane_state->src_y = src_y;
        plane_state->src_h = src_h;
        plane_state->src_w = src_w;

        ret = drm_atomic_commit(state);
        if (ret != 0)
                goto fail;

        if (plane == crtc->cursor)
                state->legacy_cursor_update = true;

        /* Driver takes ownership of state on successful commit. */
        return 0;
fail:
        if (ret == -EDEADLK)
                goto backoff;

        drm_atomic_state_free(state);

        return ret;
backoff:
        drm_atomic_state_clear(state);
        drm_atomic_legacy_backoff(state);

        /*
         * Someone might have exchanged the framebuffer while we dropped locks
         * in the backoff code. We need to fix up the fb refcount tracking the
         * core does for us.
         */
        plane->old_fb = plane->fb;

        goto retry;
}
EXPORT_SYMBOL(drm_atomic_helper_update_plane);

/**
 * drm_atomic_helper_disable_plane - Helper for primary plane disable using * atomic
 * @plane: plane to disable
 *
 * Provides a default plane disable handler using the atomic driver interface.
 *
 * RETURNS:
 * Zero on success, error code on failure
 */
int drm_atomic_helper_disable_plane(struct drm_plane *plane)
{
        struct drm_atomic_state *state;
        struct drm_plane_state *plane_state;
        int ret = 0;

        /*
         * FIXME: Without plane->crtc set we can't get at the implicit legacy
         * acquire context. The real fix will be to wire the acquire ctx through
         * everywhere we need it, but meanwhile prevent chaos by just skipping
         * this noop. The critical case is the cursor ioctls which a) only grab
         * crtc/cursor-plane locks (so we need the crtc to get at the right
         * acquire context) and b) can try to disable the plane multiple times.
         */
        if (!plane->crtc)
                return 0;

        state = drm_atomic_state_alloc(plane->dev);
        if (!state)
                return -ENOMEM;

        state->acquire_ctx = drm_modeset_legacy_acquire_ctx(plane->crtc);
retry:
        plane_state = drm_atomic_get_plane_state(state, plane);
        if (IS_ERR(plane_state)) {
                ret = PTR_ERR(plane_state);
                goto fail;
        }

        ret = drm_atomic_set_crtc_for_plane(plane_state, NULL);
        if (ret != 0)
                goto fail;
        drm_atomic_set_fb_for_plane(plane_state, NULL);
        plane_state->crtc_x = 0;
        plane_state->crtc_y = 0;
        plane_state->crtc_h = 0;
        plane_state->crtc_w = 0;
        plane_state->src_x = 0;
        plane_state->src_y = 0;
        plane_state->src_h = 0;
        plane_state->src_w = 0;

        if (plane == plane->crtc->cursor)
                state->legacy_cursor_update = true;

        ret = drm_atomic_commit(state);
        if (ret != 0)
                goto fail;

        /* Driver takes ownership of state on successful commit. */
        return 0;
fail:
        if (ret == -EDEADLK)
                goto backoff;

        drm_atomic_state_free(state);

        return ret;
backoff:
        drm_atomic_state_clear(state);
        drm_atomic_legacy_backoff(state);

        /*
         * Someone might have exchanged the framebuffer while we dropped locks
         * in the backoff code. We need to fix up the fb refcount tracking the
         * core does for us.
         */
        plane->old_fb = plane->fb;

        goto retry;
}
EXPORT_SYMBOL(drm_atomic_helper_disable_plane);

static int update_output_state(struct drm_atomic_state *state,
                               struct drm_mode_set *set)
{
        struct drm_device *dev = set->crtc->dev;
        struct drm_crtc *crtc;
        struct drm_crtc_state *crtc_state;
        struct drm_connector *connector;
        struct drm_connector_state *conn_state;
        int ret, i, j;

        ret = drm_modeset_lock(&dev->mode_config.connection_mutex,
                               state->acquire_ctx);
        if (ret)
                return ret;

        /* First grab all affected connector/crtc states. */
        for (i = 0; i < set->num_connectors; i++) {
                conn_state = drm_atomic_get_connector_state(state,
                                                            set->connectors[i]);
                if (IS_ERR(conn_state))
                        return PTR_ERR(conn_state);
        }

        for_each_crtc_in_state(state, crtc, crtc_state, i) {
                ret = drm_atomic_add_affected_connectors(state, crtc);
                if (ret)
                        return ret;
        }

        /* Then recompute connector->crtc links and crtc enabling state. */
        for_each_connector_in_state(state, connector, conn_state, i) {
                if (conn_state->crtc == set->crtc) {
                        ret = drm_atomic_set_crtc_for_connector(conn_state,
                                                                NULL);
                        if (ret)
                                return ret;
                }

                for (j = 0; j < set->num_connectors; j++) {
                        if (set->connectors[j] == connector) {
                                ret = drm_atomic_set_crtc_for_connector(conn_state,
                                                                        set->crtc);
                                if (ret)
                                        return ret;
                                break;
                        }
                }
        }

        for_each_crtc_in_state(state, crtc, crtc_state, i) {
                /* Don't update ->enable for the CRTC in the set_config request,
                 * since a mismatch would indicate a bug in the upper layers.
                 * The actual modeset code later on will catch any
                 * inconsistencies here. */
                if (crtc == set->crtc)
                        continue;

                crtc_state->enable =
                        drm_atomic_connectors_for_crtc(state, crtc);
        }

        return 0;
}

/**
 * drm_atomic_helper_set_config - set a new config from userspace
 * @set: mode set configuration
 *
 * Provides a default crtc set_config handler using the atomic driver interface.
 *
 * Returns:
 * Returns 0 on success, negative errno numbers on failure.
 */
int drm_atomic_helper_set_config(struct drm_mode_set *set)
{
        struct drm_atomic_state *state;
        struct drm_crtc *crtc = set->crtc;
        struct drm_crtc_state *crtc_state;
        struct drm_plane_state *primary_state;
        int ret = 0;

        state = drm_atomic_state_alloc(crtc->dev);
        if (!state)
                return -ENOMEM;

        state->acquire_ctx = drm_modeset_legacy_acquire_ctx(crtc);
retry:
        crtc_state = drm_atomic_get_crtc_state(state, crtc);
        if (IS_ERR(crtc_state)) {
                ret = PTR_ERR(crtc_state);
                goto fail;
        }

        primary_state = drm_atomic_get_plane_state(state, crtc->primary);
        if (IS_ERR(primary_state)) {
                ret = PTR_ERR(primary_state);
                goto fail;
        }

        if (!set->mode) {
                WARN_ON(set->fb);
                WARN_ON(set->num_connectors);

                crtc_state->enable = false;
                crtc_state->active = false;

                ret = drm_atomic_set_crtc_for_plane(primary_state, NULL);
                if (ret != 0)
                        goto fail;

                drm_atomic_set_fb_for_plane(primary_state, NULL);

                goto commit;
        }

        WARN_ON(!set->fb);
        WARN_ON(!set->num_connectors);

        crtc_state->enable = true;
        crtc_state->active = true;
        drm_mode_copy(&crtc_state->mode, set->mode);

        ret = drm_atomic_set_crtc_for_plane(primary_state, crtc);
        if (ret != 0)
                goto fail;
        drm_atomic_set_fb_for_plane(primary_state, set->fb);
        primary_state->crtc_x = 0;
        primary_state->crtc_y = 0;
        primary_state->crtc_h = set->mode->vdisplay;
        primary_state->crtc_w = set->mode->hdisplay;
        primary_state->src_x = set->x << 16;
        primary_state->src_y = set->y << 16;
        primary_state->src_h = set->mode->vdisplay << 16;
        primary_state->src_w = set->mode->hdisplay << 16;

commit:
        ret = update_output_state(state, set);
        if (ret)
                goto fail;

        ret = drm_atomic_commit(state);
        if (ret != 0)
                goto fail;

        /* Driver takes ownership of state on successful commit. */
        return 0;
fail:
        if (ret == -EDEADLK)
                goto backoff;

        drm_atomic_state_free(state);

        return ret;
backoff:
        drm_atomic_state_clear(state);
        drm_atomic_legacy_backoff(state);

        /*
         * Someone might have exchanged the framebuffer while we dropped locks
         * in the backoff code. We need to fix up the fb refcount tracking the
         * core does for us.
         */
        crtc->primary->old_fb = crtc->primary->fb;

        goto retry;
}
EXPORT_SYMBOL(drm_atomic_helper_set_config);

/**
 * drm_atomic_helper_crtc_set_property - helper for crtc properties
 * @crtc: DRM crtc
 * @property: DRM property
 * @val: value of property
 *
 * Provides a default crtc set_property handler using the atomic driver
 * interface.
 *
 * RETURNS:
 * Zero on success, error code on failure
 */
int
drm_atomic_helper_crtc_set_property(struct drm_crtc *crtc,
                                    struct drm_property *property,
                                    uint64_t val)
{
        struct drm_atomic_state *state;
        struct drm_crtc_state *crtc_state;
        int ret = 0;

        state = drm_atomic_state_alloc(crtc->dev);
        if (!state)
                return -ENOMEM;

        /* ->set_property is always called with all locks held. */
        state->acquire_ctx = crtc->dev->mode_config.acquire_ctx;
retry:
        crtc_state = drm_atomic_get_crtc_state(state, crtc);
        if (IS_ERR(crtc_state)) {
                ret = PTR_ERR(crtc_state);
                goto fail;
        }

        ret = drm_atomic_crtc_set_property(crtc, crtc_state,
                        property, val);
        if (ret)
                goto fail;

        ret = drm_atomic_commit(state);
        if (ret != 0)
                goto fail;

        /* Driver takes ownership of state on successful commit. */
        return 0;
fail:
        if (ret == -EDEADLK)
                goto backoff;

        drm_atomic_state_free(state);

        return ret;
backoff:
        drm_atomic_state_clear(state);
        drm_atomic_legacy_backoff(state);

        goto retry;
}
EXPORT_SYMBOL(drm_atomic_helper_crtc_set_property);

/**
 * drm_atomic_helper_plane_set_property - helper for plane properties
 * @plane: DRM plane
 * @property: DRM property
 * @val: value of property
 *
 * Provides a default plane set_property handler using the atomic driver
 * interface.
 *
 * RETURNS:
 * Zero on success, error code on failure
 */
int
drm_atomic_helper_plane_set_property(struct drm_plane *plane,
                                    struct drm_property *property,
                                    uint64_t val)
{
        struct drm_atomic_state *state;
        struct drm_plane_state *plane_state;
        int ret = 0;

        state = drm_atomic_state_alloc(plane->dev);
        if (!state)
                return -ENOMEM;

        /* ->set_property is always called with all locks held. */
        state->acquire_ctx = plane->dev->mode_config.acquire_ctx;
retry:
        plane_state = drm_atomic_get_plane_state(state, plane);
        if (IS_ERR(plane_state)) {
                ret = PTR_ERR(plane_state);
                goto fail;
        }

        ret = drm_atomic_plane_set_property(plane, plane_state,
                        property, val);
        if (ret)
                goto fail;

        ret = drm_atomic_commit(state);
        if (ret != 0)
                goto fail;

        /* Driver takes ownership of state on successful commit. */
        return 0;
fail:
        if (ret == -EDEADLK)
                goto backoff;

        drm_atomic_state_free(state);

        return ret;
backoff:
        drm_atomic_state_clear(state);
        drm_atomic_legacy_backoff(state);

        goto retry;
}
EXPORT_SYMBOL(drm_atomic_helper_plane_set_property);

/**
 * drm_atomic_helper_connector_set_property - helper for connector properties
 * @connector: DRM connector
 * @property: DRM property
 * @val: value of property
 *
 * Provides a default connector set_property handler using the atomic driver
 * interface.
 *
 * RETURNS:
 * Zero on success, error code on failure
 */
int
drm_atomic_helper_connector_set_property(struct drm_connector *connector,
                                    struct drm_property *property,
                                    uint64_t val)
{
        struct drm_atomic_state *state;
        struct drm_connector_state *connector_state;
        int ret = 0;

        state = drm_atomic_state_alloc(connector->dev);
        if (!state)
                return -ENOMEM;

        /* ->set_property is always called with all locks held. */
        state->acquire_ctx = connector->dev->mode_config.acquire_ctx;
retry:
        connector_state = drm_atomic_get_connector_state(state, connector);
        if (IS_ERR(connector_state)) {
                ret = PTR_ERR(connector_state);
                goto fail;
        }

        ret = drm_atomic_connector_set_property(connector, connector_state,
                        property, val);
        if (ret)
                goto fail;

        ret = drm_atomic_commit(state);
        if (ret != 0)
                goto fail;

        /* Driver takes ownership of state on successful commit. */
        return 0;
fail:
        if (ret == -EDEADLK)
                goto backoff;

        drm_atomic_state_free(state);

        return ret;
backoff:
        drm_atomic_state_clear(state);
        drm_atomic_legacy_backoff(state);

        goto retry;
}
EXPORT_SYMBOL(drm_atomic_helper_connector_set_property);

/**
 * drm_atomic_helper_page_flip - execute a legacy page flip
 * @crtc: DRM crtc
 * @fb: DRM framebuffer
 * @event: optional DRM event to signal upon completion
 * @flags: flip flags for non-vblank sync'ed updates
 *
 * Provides a default page flip implementation using the atomic driver interface.
 *
 * Note that for now so called async page flips (i.e. updates which are not
 * synchronized to vblank) are not supported, since the atomic interfaces have
 * no provisions for this yet.
 *
 * Returns:
 * Returns 0 on success, negative errno numbers on failure.
 */
int drm_atomic_helper_page_flip(struct drm_crtc *crtc,
                                struct drm_framebuffer *fb,
                                struct drm_pending_vblank_event *event,
                                uint32_t flags)
{
        struct drm_plane *plane = crtc->primary;
        struct drm_atomic_state *state;
        struct drm_plane_state *plane_state;
        struct drm_crtc_state *crtc_state;
        int ret = 0;

        if (flags & DRM_MODE_PAGE_FLIP_ASYNC)
                return -EINVAL;

        state = drm_atomic_state_alloc(plane->dev);
        if (!state)
                return -ENOMEM;

        state->acquire_ctx = drm_modeset_legacy_acquire_ctx(crtc);
retry:
        crtc_state = drm_atomic_get_crtc_state(state, crtc);
        if (IS_ERR(crtc_state)) {
                ret = PTR_ERR(crtc_state);
                goto fail;
        }
        crtc_state->event = event;

        plane_state = drm_atomic_get_plane_state(state, plane);
        if (IS_ERR(plane_state)) {
                ret = PTR_ERR(plane_state);
                goto fail;
        }

        ret = drm_atomic_set_crtc_for_plane(plane_state, crtc);
        if (ret != 0)
                goto fail;
        drm_atomic_set_fb_for_plane(plane_state, fb);

        ret = drm_atomic_async_commit(state);
        if (ret != 0)
                goto fail;

        /* TODO: ->page_flip is the only driver callback where the core
         * doesn't update plane->fb. For now patch it up here. */
        plane->fb = plane->state->fb;

        /* Driver takes ownership of state on successful async commit. */
        return 0;
fail:
        if (ret == -EDEADLK)
                goto backoff;

        drm_atomic_state_free(state);

        return ret;
backoff:
        drm_atomic_state_clear(state);
        drm_atomic_legacy_backoff(state);

        /*
         * Someone might have exchanged the framebuffer while we dropped locks
         * in the backoff code. We need to fix up the fb refcount tracking the
         * core does for us.
         */
        plane->old_fb = plane->fb;

        goto retry;
}
EXPORT_SYMBOL(drm_atomic_helper_page_flip);

/**
 * drm_atomic_helper_connector_dpms() - connector dpms helper implementation
 * @connector: affected connector
 * @mode: DPMS mode
 *
 * This is the main helper function provided by the atomic helper framework for
 * implementing the legacy DPMS connector interface. It computes the new desired
 * ->active state for the corresponding CRTC (if the connector is enabled) and
 *  updates it.
 */
void drm_atomic_helper_connector_dpms(struct drm_connector *connector,
                                      int mode)
{
        struct drm_mode_config *config = &connector->dev->mode_config;
        struct drm_atomic_state *state;
        struct drm_crtc_state *crtc_state;
        struct drm_crtc *crtc;
        struct drm_connector *tmp_connector;
        int ret;
        bool active = false;

        if (mode != DRM_MODE_DPMS_ON)
                mode = DRM_MODE_DPMS_OFF;

        connector->dpms = mode;
        crtc = connector->state->crtc;

        if (!crtc)
                return;

        /* FIXME: ->dpms has no return value so can't forward the -ENOMEM. */
        state = drm_atomic_state_alloc(connector->dev);
        if (!state)
                return;

        state->acquire_ctx = drm_modeset_legacy_acquire_ctx(crtc);
retry:
        crtc_state = drm_atomic_get_crtc_state(state, crtc);
        if (IS_ERR(crtc_state))
                return;

        WARN_ON(!drm_modeset_is_locked(&config->connection_mutex));

        list_for_each_entry(tmp_connector, &config->connector_list, head) {
                if (tmp_connector->state->crtc != crtc)
                        continue;

                if (tmp_connector->dpms == DRM_MODE_DPMS_ON) {
                        active = true;
                        break;
                }
        }
        crtc_state->active = active;

        ret = drm_atomic_commit(state);
        if (ret != 0)
                goto fail;

        /* Driver takes ownership of state on successful async commit. */
        return;
fail:
        if (ret == -EDEADLK)
                goto backoff;

        drm_atomic_state_free(state);

        WARN(1, "Driver bug: Changing ->active failed with ret=%i\n", ret);

        return;
backoff:
        drm_atomic_state_clear(state);
        drm_atomic_legacy_backoff(state);

        goto retry;
}
EXPORT_SYMBOL(drm_atomic_helper_connector_dpms);

/**
 * DOC: atomic state reset and initialization
 *
 * Both the drm core and the atomic helpers assume that there is always the full
 * and correct atomic software state for all connectors, CRTCs and planes
 * available. Which is a bit a problem on driver load and also after system
 * suspend. One way to solve this is to have a hardware state read-out
 * infrastructure which reconstructs the full software state (e.g. the i915
 * driver).
 *
 * The simpler solution is to just reset the software state to everything off,
 * which is easiest to do by calling drm_mode_config_reset(). To facilitate this
 * the atomic helpers provide default reset implementations for all hooks.
 */

/**
 * drm_atomic_helper_crtc_reset - default ->reset hook for CRTCs
 * @crtc: drm CRTC
 *
 * Resets the atomic state for @crtc by freeing the state pointer (which might
 * be NULL, e.g. at driver load time) and allocating a new empty state object.
 */
void drm_atomic_helper_crtc_reset(struct drm_crtc *crtc)
{
        kfree(crtc->state);
        crtc->state = kzalloc(sizeof(*crtc->state), GFP_KERNEL);

        if (crtc->state)
                crtc->state->crtc = crtc;
}
EXPORT_SYMBOL(drm_atomic_helper_crtc_reset);

/**
 * __drm_atomic_helper_crtc_duplicate_state - copy atomic CRTC state
 * @crtc: CRTC object
 * @state: atomic CRTC state
 *
 * Copies atomic state from a CRTC's current state and resets inferred values.
 * This is useful for drivers that subclass the CRTC state.
 */
void __drm_atomic_helper_crtc_duplicate_state(struct drm_crtc *crtc,
                                              struct drm_crtc_state *state)
{
        memcpy(state, crtc->state, sizeof(*state));

        state->mode_changed = false;
        state->active_changed = false;
        state->planes_changed = false;
        state->event = NULL;
}
EXPORT_SYMBOL(__drm_atomic_helper_crtc_duplicate_state);

/**
 * drm_atomic_helper_crtc_duplicate_state - default state duplicate hook
 * @crtc: drm CRTC
 *
 * Default CRTC state duplicate hook for drivers which don't have their own
 * subclassed CRTC state structure.
 */
struct drm_crtc_state *
drm_atomic_helper_crtc_duplicate_state(struct drm_crtc *crtc)
{
        struct drm_crtc_state *state;

        if (WARN_ON(!crtc->state))

                return NULL;

        state = kmalloc(sizeof(*state), GFP_KERNEL);
        if (state)
                __drm_atomic_helper_crtc_duplicate_state(crtc, state);

        return state;
}
EXPORT_SYMBOL(drm_atomic_helper_crtc_duplicate_state);

/**
 * __drm_atomic_helper_crtc_destroy_state - release CRTC state
 * @crtc: CRTC object
 * @state: CRTC state object to release
 *
 * Releases all resources stored in the CRTC state without actually freeing
 * the memory of the CRTC state. This is useful for drivers that subclass the
 * CRTC state.
 */
void __drm_atomic_helper_crtc_destroy_state(struct drm_crtc *crtc,
                                            struct drm_crtc_state *state)
{
        /*
         * This is currently a placeholder so that drivers that subclass the
         * state will automatically do the right thing if code is ever added
         * to this function.
         */
}
EXPORT_SYMBOL(__drm_atomic_helper_crtc_destroy_state);

/**
 * drm_atomic_helper_crtc_destroy_state - default state destroy hook
 * @crtc: drm CRTC
 * @state: CRTC state object to release
 *
 * Default CRTC state destroy hook for drivers which don't have their own
 * subclassed CRTC state structure.
 */
void drm_atomic_helper_crtc_destroy_state(struct drm_crtc *crtc,
                                          struct drm_crtc_state *state)
{
        __drm_atomic_helper_crtc_destroy_state(crtc, state);
        kfree(state);
}
EXPORT_SYMBOL(drm_atomic_helper_crtc_destroy_state);

/**
 * drm_atomic_helper_plane_reset - default ->reset hook for planes
 * @plane: drm plane
 *
 * Resets the atomic state for @plane by freeing the state pointer (which might
 * be NULL, e.g. at driver load time) and allocating a new empty state object.
 */
void drm_atomic_helper_plane_reset(struct drm_plane *plane)
{
        if (plane->state && plane->state->fb)
                drm_framebuffer_unreference(plane->state->fb);

        kfree(plane->state);
        plane->state = kzalloc(sizeof(*plane->state), GFP_KERNEL);

        if (plane->state)
                plane->state->plane = plane;
}
EXPORT_SYMBOL(drm_atomic_helper_plane_reset);

/**
 * __drm_atomic_helper_plane_duplicate_state - copy atomic plane state
 * @plane: plane object
 * @state: atomic plane state
 *
 * Copies atomic state from a plane's current state. This is useful for
 * drivers that subclass the plane state.
 */
void __drm_atomic_helper_plane_duplicate_state(struct drm_plane *plane,
                                               struct drm_plane_state *state)
{
        memcpy(state, plane->state, sizeof(*state));

        if (state->fb)
                drm_framebuffer_reference(state->fb);
}
EXPORT_SYMBOL(__drm_atomic_helper_plane_duplicate_state);

/**
 * drm_atomic_helper_plane_duplicate_state - default state duplicate hook
 * @plane: drm plane
 *
 * Default plane state duplicate hook for drivers which don't have their own
 * subclassed plane state structure.
 */
struct drm_plane_state *
drm_atomic_helper_plane_duplicate_state(struct drm_plane *plane)
{
        struct drm_plane_state *state;

        if (WARN_ON(!plane->state))
                return NULL;

        state = kmalloc(sizeof(*state), GFP_KERNEL);
        if (state)
                __drm_atomic_helper_plane_duplicate_state(plane, state);

        return state;
}
EXPORT_SYMBOL(drm_atomic_helper_plane_duplicate_state);

/**
 * __drm_atomic_helper_plane_destroy_state - release plane state
 * @plane: plane object
 * @state: plane state object to release
 *
 * Releases all resources stored in the plane state without actually freeing
 * the memory of the plane state. This is useful for drivers that subclass the
 * plane state.
 */
void __drm_atomic_helper_plane_destroy_state(struct drm_plane *plane,
                                             struct drm_plane_state *state)
{
        if (state->fb)
                drm_framebuffer_unreference(state->fb);
}
EXPORT_SYMBOL(__drm_atomic_helper_plane_destroy_state);

/**
 * drm_atomic_helper_plane_destroy_state - default state destroy hook
 * @plane: drm plane
 * @state: plane state object to release
 *
 * Default plane state destroy hook for drivers which don't have their own
 * subclassed plane state structure.
 */
void drm_atomic_helper_plane_destroy_state(struct drm_plane *plane,
                                           struct drm_plane_state *state)
{
        __drm_atomic_helper_plane_destroy_state(plane, state);
        kfree(state);
}
EXPORT_SYMBOL(drm_atomic_helper_plane_destroy_state);

/**
 * drm_atomic_helper_connector_reset - default ->reset hook for connectors
 * @connector: drm connector
 *
 * Resets the atomic state for @connector by freeing the state pointer (which
 * might be NULL, e.g. at driver load time) and allocating a new empty state
 * object.
 */
void drm_atomic_helper_connector_reset(struct drm_connector *connector)
{
        kfree(connector->state);
        connector->state = kzalloc(sizeof(*connector->state), GFP_KERNEL);

        if (connector->state)
                connector->state->connector = connector;
}
EXPORT_SYMBOL(drm_atomic_helper_connector_reset);

/**
 * __drm_atomic_helper_connector_duplicate_state - copy atomic connector state
 * @connector: connector object
 * @state: atomic connector state
 *
 * Copies atomic state from a connector's current state. This is useful for
 * drivers that subclass the connector state.
 */
void
__drm_atomic_helper_connector_duplicate_state(struct drm_connector *connector,
                                            struct drm_connector_state *state)
{
        memcpy(state, connector->state, sizeof(*state));
}
EXPORT_SYMBOL(__drm_atomic_helper_connector_duplicate_state);

/**
 * drm_atomic_helper_connector_duplicate_state - default state duplicate hook
 * @connector: drm connector
 *
 * Default connector state duplicate hook for drivers which don't have their own
 * subclassed connector state structure.
 */
struct drm_connector_state *
drm_atomic_helper_connector_duplicate_state(struct drm_connector *connector)
{
        struct drm_connector_state *state;

        if (WARN_ON(!connector->state))
                return NULL;

        state = kmalloc(sizeof(*state), GFP_KERNEL);
        if (state)
                __drm_atomic_helper_connector_duplicate_state(connector, state);

        return state;
}
EXPORT_SYMBOL(drm_atomic_helper_connector_duplicate_state);

/**
 * __drm_atomic_helper_connector_destroy_state - release connector state
 * @connector: connector object
 * @state: connector state object to release
 *
 * Releases all resources stored in the connector state without actually
 * freeing the memory of the connector state. This is useful for drivers that
 * subclass the connector state.
 */
void
__drm_atomic_helper_connector_destroy_state(struct drm_connector *connector,
                                            struct drm_connector_state *state)
{
        /*
         * This is currently a placeholder so that drivers that subclass the
         * state will automatically do the right thing if code is ever added
         * to this function.
         */
}
EXPORT_SYMBOL(__drm_atomic_helper_connector_destroy_state);

/**
 * drm_atomic_helper_connector_destroy_state - default state destroy hook
 * @connector: drm connector
 * @state: connector state object to release
 *
 * Default connector state destroy hook for drivers which don't have their own
 * subclassed connector state structure.
 */
void drm_atomic_helper_connector_destroy_state(struct drm_connector *connector,
                                          struct drm_connector_state *state)
{
        __drm_atomic_helper_connector_destroy_state(connector, state);
        kfree(state);
}
EXPORT_SYMBOL(drm_atomic_helper_connector_destroy_state);