/*
 * Copyright 2015 Advanced Micro Devices, Inc.
 *
 * 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: AMD
 *
 */

#include <linux/string.h>
#include <linux/acpi.h>
#include <linux/i2c.h>

#include <drm/drm_probe_helper.h>
#include <drm/amdgpu_drm.h>
#include <drm/drm_edid.h>

#include "dm_services.h"
#include "amdgpu.h"
#include "dc.h"
#include "amdgpu_dm.h"
#include "amdgpu_dm_irq.h"
#include "amdgpu_dm_mst_types.h"

#include "dm_helpers.h"

struct monitor_patch_info {
        unsigned int manufacturer_id;
        unsigned int product_id;
        void (*patch_func)(struct dc_edid_caps *edid_caps, unsigned int param);
        unsigned int patch_param;
};
static void set_max_dsc_bpp_limit(struct dc_edid_caps *edid_caps, unsigned int param);

static const struct monitor_patch_info monitor_patch_table[] = {
{0x6D1E, 0x5BBF, set_max_dsc_bpp_limit, 15},
{0x6D1E, 0x5B9A, set_max_dsc_bpp_limit, 15},
};

static void set_max_dsc_bpp_limit(struct dc_edid_caps *edid_caps, unsigned int param)
{
        if (edid_caps)
                edid_caps->panel_patch.max_dsc_target_bpp_limit = param;
}

static int amdgpu_dm_patch_edid_caps(struct dc_edid_caps *edid_caps)
{
        int i, ret = 0;

        for (i = 0; i < ARRAY_SIZE(monitor_patch_table); i++)
                if ((edid_caps->manufacturer_id == monitor_patch_table[i].manufacturer_id)
                        &&  (edid_caps->product_id == monitor_patch_table[i].product_id)) {
                        monitor_patch_table[i].patch_func(edid_caps, monitor_patch_table[i].patch_param);
                        ret++;
                }

        return ret;
}

/* dm_helpers_parse_edid_caps
 *
 * Parse edid caps
 *
 * @edid:       [in] pointer to edid
 *  edid_caps:  [in] pointer to edid caps
 * @return
 *      void
 * */
enum dc_edid_status dm_helpers_parse_edid_caps(
                struct dc_context *ctx,
                const struct dc_edid *edid,
                struct dc_edid_caps *edid_caps)
{
        struct edid *edid_buf = (struct edid *) edid->raw_edid;
        struct cea_sad *sads;
        int sad_count = -1;
        int sadb_count = -1;
        int i = 0;
        int j = 0;
        uint8_t *sadb = NULL;

        enum dc_edid_status result = EDID_OK;

        if (!edid_caps || !edid)
                return EDID_BAD_INPUT;

        if (!drm_edid_is_valid(edid_buf))
                result = EDID_BAD_CHECKSUM;

        edid_caps->manufacturer_id = (uint16_t) edid_buf->mfg_id[0] |
                                        ((uint16_t) edid_buf->mfg_id[1])<<8;
        edid_caps->product_id = (uint16_t) edid_buf->prod_code[0] |
                                        ((uint16_t) edid_buf->prod_code[1])<<8;
        edid_caps->serial_number = edid_buf->serial;
        edid_caps->manufacture_week = edid_buf->mfg_week;
        edid_caps->manufacture_year = edid_buf->mfg_year;

        /* One of the four detailed_timings stores the monitor name. It's
         * stored in an array of length 13. */
        for (i = 0; i < 4; i++) {
                if (edid_buf->detailed_timings[i].data.other_data.type == 0xfc) {
                        while (j < 13 && edid_buf->detailed_timings[i].data.other_data.data.str.str[j]) {
                                if (edid_buf->detailed_timings[i].data.other_data.data.str.str[j] == '\n')
                                        break;

                                edid_caps->display_name[j] =
                                        edid_buf->detailed_timings[i].data.other_data.data.str.str[j];
                                j++;
                        }
                }
        }

        edid_caps->edid_hdmi = drm_detect_hdmi_monitor(
                        (struct edid *) edid->raw_edid);

        sad_count = drm_edid_to_sad((struct edid *) edid->raw_edid, &sads);
        if (sad_count <= 0)
                return result;

        edid_caps->audio_mode_count = sad_count < DC_MAX_AUDIO_DESC_COUNT ? sad_count : DC_MAX_AUDIO_DESC_COUNT;
        for (i = 0; i < edid_caps->audio_mode_count; ++i) {
                struct cea_sad *sad = &sads[i];

                edid_caps->audio_modes[i].format_code = sad->format;
                edid_caps->audio_modes[i].channel_count = sad->channels + 1;
                edid_caps->audio_modes[i].sample_rate = sad->freq;
                edid_caps->audio_modes[i].sample_size = sad->byte2;
        }

        sadb_count = drm_edid_to_speaker_allocation((struct edid *) edid->raw_edid, &sadb);

        if (sadb_count < 0) {
                DRM_ERROR("Couldn't read Speaker Allocation Data Block: %d\n", sadb_count);
                sadb_count = 0;
        }

        if (sadb_count)
                edid_caps->speaker_flags = sadb[0];
        else
                edid_caps->speaker_flags = DEFAULT_SPEAKER_LOCATION;

        kfree(sads);
        kfree(sadb);

        amdgpu_dm_patch_edid_caps(edid_caps);

        return result;
}

static void get_payload_table(
                struct amdgpu_dm_connector *aconnector,
                struct dp_mst_stream_allocation_table *proposed_table)
{
        int i;
        struct drm_dp_mst_topology_mgr *mst_mgr =
                        &aconnector->mst_port->mst_mgr;

        mutex_lock(&mst_mgr->payload_lock);

        proposed_table->stream_count = 0;

        /* number of active streams */
        for (i = 0; i < mst_mgr->max_payloads; i++) {
                if (mst_mgr->payloads[i].num_slots == 0)
                        break; /* end of vcp_id table */

                ASSERT(mst_mgr->payloads[i].payload_state !=
                                DP_PAYLOAD_DELETE_LOCAL);

                if (mst_mgr->payloads[i].payload_state == DP_PAYLOAD_LOCAL ||
                        mst_mgr->payloads[i].payload_state ==
                                        DP_PAYLOAD_REMOTE) {

                        struct dp_mst_stream_allocation *sa =
                                        &proposed_table->stream_allocations[
                                                proposed_table->stream_count];

                        sa->slot_count = mst_mgr->payloads[i].num_slots;
                        sa->vcp_id = mst_mgr->proposed_vcpis[i]->vcpi;
                        proposed_table->stream_count++;
                }
        }

        mutex_unlock(&mst_mgr->payload_lock);
}

void dm_helpers_dp_update_branch_info(
        struct dc_context *ctx,
        const struct dc_link *link)
{}

/*
 * Writes payload allocation table in immediate downstream device.
 */
bool dm_helpers_dp_mst_write_payload_allocation_table(
                struct dc_context *ctx,
                const struct dc_stream_state *stream,
                struct dp_mst_stream_allocation_table *proposed_table,
                bool enable)
{
        struct amdgpu_dm_connector *aconnector;
        struct dm_connector_state *dm_conn_state;
        struct drm_dp_mst_topology_mgr *mst_mgr;
        struct drm_dp_mst_port *mst_port;
        bool ret;

        aconnector = (struct amdgpu_dm_connector *)stream->dm_stream_context;
        /* Accessing the connector state is required for vcpi_slots allocation
         * and directly relies on behaviour in commit check
         * that blocks before commit guaranteeing that the state
         * is not gonna be swapped while still in use in commit tail */

        if (!aconnector || !aconnector->mst_port)
                return false;

        dm_conn_state = to_dm_connector_state(aconnector->base.state);

        mst_mgr = &aconnector->mst_port->mst_mgr;

        if (!mst_mgr->mst_state)
                return false;

        mst_port = aconnector->port;

        if (enable) {

                ret = drm_dp_mst_allocate_vcpi(mst_mgr, mst_port,
                                               dm_conn_state->pbn,
                                               dm_conn_state->vcpi_slots);
                if (!ret)
                        return false;

        } else {
                drm_dp_mst_reset_vcpi_slots(mst_mgr, mst_port);
        }

        /* It's OK for this to fail */
        drm_dp_update_payload_part1(mst_mgr);

        /* mst_mgr->->payloads are VC payload notify MST branch using DPCD or
         * AUX message. The sequence is slot 1-63 allocated sequence for each
         * stream. AMD ASIC stream slot allocation should follow the same
         * sequence. copy DRM MST allocation to dc */

        get_payload_table(aconnector, proposed_table);

        return true;
}

/*
 * poll pending down reply
 */
void dm_helpers_dp_mst_poll_pending_down_reply(
        struct dc_context *ctx,
        const struct dc_link *link)
{}

/*
 * Clear payload allocation table before enable MST DP link.
 */
void dm_helpers_dp_mst_clear_payload_allocation_table(
        struct dc_context *ctx,
        const struct dc_link *link)
{}

/*
 * Polls for ACT (allocation change trigger) handled and sends
 * ALLOCATE_PAYLOAD message.
 */
enum act_return_status dm_helpers_dp_mst_poll_for_allocation_change_trigger(
                struct dc_context *ctx,
                const struct dc_stream_state *stream)
{
        struct amdgpu_dm_connector *aconnector;
        struct drm_dp_mst_topology_mgr *mst_mgr;
        int ret;

        aconnector = (struct amdgpu_dm_connector *)stream->dm_stream_context;

        if (!aconnector || !aconnector->mst_port)
                return ACT_FAILED;

        mst_mgr = &aconnector->mst_port->mst_mgr;

        if (!mst_mgr->mst_state)
                return ACT_FAILED;

        ret = drm_dp_check_act_status(mst_mgr);

        if (ret)
                return ACT_FAILED;

        return ACT_SUCCESS;
}

bool dm_helpers_dp_mst_send_payload_allocation(
                struct dc_context *ctx,
                const struct dc_stream_state *stream,
                bool enable)
{
        struct amdgpu_dm_connector *aconnector;
        struct drm_dp_mst_topology_mgr *mst_mgr;
        struct drm_dp_mst_port *mst_port;

        aconnector = (struct amdgpu_dm_connector *)stream->dm_stream_context;

        if (!aconnector || !aconnector->mst_port)
                return false;

        mst_port = aconnector->port;

        mst_mgr = &aconnector->mst_port->mst_mgr;

        if (!mst_mgr->mst_state)
                return false;

        /* It's OK for this to fail */
        drm_dp_update_payload_part2(mst_mgr);

        if (!enable)
                drm_dp_mst_deallocate_vcpi(mst_mgr, mst_port);

        return true;
}

void dm_dtn_log_begin(struct dc_context *ctx,
        struct dc_log_buffer_ctx *log_ctx)
{
        static const char msg[] = "[dtn begin]\n";

        if (!log_ctx) {
                pr_info("%s", msg);
                return;
        }

        dm_dtn_log_append_v(ctx, log_ctx, "%s", msg);
}

__printf(3, 4)
void dm_dtn_log_append_v(struct dc_context *ctx,
        struct dc_log_buffer_ctx *log_ctx,
        const char *msg, ...)
{
        va_list args;
        size_t total;
        int n;

        if (!log_ctx) {
                /* No context, redirect to dmesg. */
                struct va_format vaf;

                vaf.fmt = msg;
                vaf.va = &args;

                va_start(args, msg);
                pr_info("%pV", &vaf);
                va_end(args);

                return;
        }

        /* Measure the output. */
        va_start(args, msg);
        n = vsnprintf(NULL, 0, msg, args);
        va_end(args);

        if (n <= 0)
                return;

        /* Reallocate the string buffer as needed. */
        total = log_ctx->pos + n + 1;

        if (total > log_ctx->size) {
                char *buf = (char *)kvcalloc(total, sizeof(char), GFP_KERNEL);

                if (buf) {
                        memcpy(buf, log_ctx->buf, log_ctx->pos);
                        kfree(log_ctx->buf);

                        log_ctx->buf = buf;
                        log_ctx->size = total;
                }
        }

        if (!log_ctx->buf)
                return;

        /* Write the formatted string to the log buffer. */
        va_start(args, msg);
        n = vscnprintf(
                log_ctx->buf + log_ctx->pos,
                log_ctx->size - log_ctx->pos,
                msg,
                args);
        va_end(args);

        if (n > 0)
                log_ctx->pos += n;
}

void dm_dtn_log_end(struct dc_context *ctx,
        struct dc_log_buffer_ctx *log_ctx)
{
        static const char msg[] = "[dtn end]\n";

        if (!log_ctx) {
                pr_info("%s", msg);
                return;
        }

        dm_dtn_log_append_v(ctx, log_ctx, "%s", msg);
}

bool dm_helpers_dp_mst_start_top_mgr(
                struct dc_context *ctx,
                const struct dc_link *link,
                bool boot)
{
        struct amdgpu_dm_connector *aconnector = link->priv;

        if (!aconnector) {
                DRM_ERROR("Failed to find connector for link!");
                return false;
        }

        if (boot) {
                DRM_INFO("DM_MST: Differing MST start on aconnector: %p [id: %d]\n",
                                        aconnector, aconnector->base.base.id);
                return true;
        }

        DRM_INFO("DM_MST: starting TM on aconnector: %p [id: %d]\n",
                        aconnector, aconnector->base.base.id);

        return (drm_dp_mst_topology_mgr_set_mst(&aconnector->mst_mgr, true) == 0);
}

void dm_helpers_dp_mst_stop_top_mgr(
                struct dc_context *ctx,
                struct dc_link *link)
{
        struct amdgpu_dm_connector *aconnector = link->priv;
        uint8_t i;

        if (!aconnector) {
                DRM_ERROR("Failed to find connector for link!");
                return;
        }

        DRM_INFO("DM_MST: stopping TM on aconnector: %p [id: %d]\n",
                        aconnector, aconnector->base.base.id);

        if (aconnector->mst_mgr.mst_state == true) {
                drm_dp_mst_topology_mgr_set_mst(&aconnector->mst_mgr, false);

                for (i = 0; i < MAX_SINKS_PER_LINK; i++) {
                        if (link->remote_sinks[i] == NULL)
                                continue;

                        if (link->remote_sinks[i]->sink_signal ==
                            SIGNAL_TYPE_DISPLAY_PORT_MST) {
                                dc_link_remove_remote_sink(link, link->remote_sinks[i]);

                                if (aconnector->dc_sink) {
                                        dc_sink_release(aconnector->dc_sink);
                                        aconnector->dc_sink = NULL;
                                        aconnector->dc_link->cur_link_settings.lane_count = 0;
                                }
                        }
                }
        }
}

bool dm_helpers_dp_read_dpcd(
                struct dc_context *ctx,
                const struct dc_link *link,
                uint32_t address,
                uint8_t *data,
                uint32_t size)
{

        struct amdgpu_dm_connector *aconnector = link->priv;

        if (!aconnector) {
                DC_LOG_DC("Failed to find connector for link!\n");
                return false;
        }

        return drm_dp_dpcd_read(&aconnector->dm_dp_aux.aux, address,
                        data, size) > 0;
}

bool dm_helpers_dp_write_dpcd(
                struct dc_context *ctx,
                const struct dc_link *link,
                uint32_t address,
                const uint8_t *data,
                uint32_t size)
{
        struct amdgpu_dm_connector *aconnector = link->priv;

        if (!aconnector) {
                DRM_ERROR("Failed to find connector for link!");
                return false;
        }

        return drm_dp_dpcd_write(&aconnector->dm_dp_aux.aux,
                        address, (uint8_t *)data, size) > 0;
}

bool dm_helpers_submit_i2c(
                struct dc_context *ctx,
                const struct dc_link *link,
                struct i2c_command *cmd)
{
        struct amdgpu_dm_connector *aconnector = link->priv;
        struct i2c_msg *msgs;
        int i = 0;
        int num = cmd->number_of_payloads;
        bool result;

        if (!aconnector) {
                DRM_ERROR("Failed to find connector for link!");
                return false;
        }

        msgs = kcalloc(num, sizeof(struct i2c_msg), GFP_KERNEL);

        if (!msgs)
                return false;

        for (i = 0; i < num; i++) {
                msgs[i].flags = cmd->payloads[i].write ? 0 : I2C_M_RD;
                msgs[i].addr = cmd->payloads[i].address;
                msgs[i].len = cmd->payloads[i].length;
                msgs[i].buf = cmd->payloads[i].data;
        }

        result = i2c_transfer(&aconnector->i2c->base, msgs, num) == num;

        kfree(msgs);

        return result;
}
bool dm_helpers_dp_write_dsc_enable(
                struct dc_context *ctx,
                const struct dc_stream_state *stream,
                bool enable)
{
        uint8_t enable_dsc = enable ? 1 : 0;
        struct amdgpu_dm_connector *aconnector;
        uint8_t ret = 0;

        if (!stream)
                return false;

        if (stream->signal == SIGNAL_TYPE_DISPLAY_PORT_MST) {
                aconnector = (struct amdgpu_dm_connector *)stream->dm_stream_context;

                if (!aconnector->dsc_aux)
                        return false;

                ret = drm_dp_dpcd_write(aconnector->dsc_aux, DP_DSC_ENABLE, &enable_dsc, 1);
        }

        if (stream->signal == SIGNAL_TYPE_DISPLAY_PORT) {
                ret = dm_helpers_dp_write_dpcd(ctx, stream->link, DP_DSC_ENABLE, &enable_dsc, 1);
                DC_LOG_DC("Send DSC %s to sst display\n", enable_dsc ? "enable" : "disable");
        }

        return (ret > 0);
}

bool dm_helpers_is_dp_sink_present(struct dc_link *link)
{
        bool dp_sink_present;
        struct amdgpu_dm_connector *aconnector = link->priv;

        if (!aconnector) {
                BUG_ON("Failed to find connector for link!");
                return true;
        }

        mutex_lock(&aconnector->dm_dp_aux.aux.hw_mutex);
        dp_sink_present = dc_link_is_dp_sink_present(link);
        mutex_unlock(&aconnector->dm_dp_aux.aux.hw_mutex);
        return dp_sink_present;
}

enum dc_edid_status dm_helpers_read_local_edid(
                struct dc_context *ctx,
                struct dc_link *link,
                struct dc_sink *sink)
{
        struct amdgpu_dm_connector *aconnector = link->priv;
        struct drm_connector *connector = &aconnector->base;
        struct i2c_adapter *ddc;
        int retry = 3;
        enum dc_edid_status edid_status;
        struct edid *edid;

        if (link->aux_mode)
                ddc = &aconnector->dm_dp_aux.aux.ddc;
        else
                ddc = &aconnector->i2c->base;

        /* some dongles read edid incorrectly the first time,
         * do check sum and retry to make sure read correct edid.
         */
        do {

                edid = drm_get_edid(&aconnector->base, ddc);

                /* DP Compliance Test 4.2.2.6 */
                if (link->aux_mode && connector->edid_corrupt)
                        drm_dp_send_real_edid_checksum(&aconnector->dm_dp_aux.aux, connector->real_edid_checksum);

                if (!edid && connector->edid_corrupt) {
                        connector->edid_corrupt = false;
                        return EDID_BAD_CHECKSUM;
                }

                if (!edid)
                        return EDID_NO_RESPONSE;

                sink->dc_edid.length = EDID_LENGTH * (edid->extensions + 1);
                memmove(sink->dc_edid.raw_edid, (uint8_t *)edid, sink->dc_edid.length);

                /* We don't need the original edid anymore */
                kfree(edid);

                /* connector->display_info will be parsed from EDID and saved
                 * into drm_connector->display_info from edid by call stack
                 * below:
                 * drm_parse_ycbcr420_deep_color_info
                 * drm_parse_hdmi_forum_vsdb
                 * drm_parse_cea_ext
                 * drm_add_display_info
                 * drm_connector_update_edid_property
                 *
                 * drm_connector->display_info will be used by amdgpu_dm funcs,
                 * like fill_stream_properties_from_drm_display_mode
                 */
                amdgpu_dm_update_connector_after_detect(aconnector);

                edid_status = dm_helpers_parse_edid_caps(
                                                ctx,
                                                &sink->dc_edid,
                                                &sink->edid_caps);

        } while (edid_status == EDID_BAD_CHECKSUM && --retry > 0);

        if (edid_status != EDID_OK)
                DRM_ERROR("EDID err: %d, on connector: %s",
                                edid_status,
                                aconnector->base.name);

        /* DP Compliance Test 4.2.2.3 */
        if (link->aux_mode)
                drm_dp_send_real_edid_checksum(&aconnector->dm_dp_aux.aux, sink->dc_edid.raw_edid[sink->dc_edid.length-1]);

        return edid_status;
}
int dm_helper_dmub_aux_transfer_sync(
                struct dc_context *ctx,
                const struct dc_link *link,
                struct aux_payload *payload,
                enum aux_return_code_type *operation_result)
{
        return amdgpu_dm_process_dmub_aux_transfer_sync(ctx, link->link_index, payload, operation_result);
}
void dm_set_dcn_clocks(struct dc_context *ctx, struct dc_clocks *clks)
{
        /* TODO: something */
}

void dm_helpers_smu_timeout(struct dc_context *ctx, unsigned int msg_id, unsigned int param, unsigned int timeout_us)
{
        // TODO:
        //amdgpu_device_gpu_recover(dc_context->driver-context, NULL);
}

void *dm_helpers_allocate_gpu_mem(
                struct dc_context *ctx,
                enum dc_gpu_mem_alloc_type type,
                size_t size,
                long long *addr)
{
        struct amdgpu_device *adev = ctx->driver_context;
        struct dal_allocation *da;
        u32 domain = (type == DC_MEM_ALLOC_TYPE_GART) ?
                AMDGPU_GEM_DOMAIN_GTT : AMDGPU_GEM_DOMAIN_VRAM;
        int ret;

        da = kzalloc(sizeof(struct dal_allocation), GFP_KERNEL);
        if (!da)
                return NULL;

        ret = amdgpu_bo_create_kernel(adev, size, PAGE_SIZE,
                                      domain, &da->bo,
                                      &da->gpu_addr, &da->cpu_ptr);

        *addr = da->gpu_addr;

        if (ret) {
                kfree(da);
                return NULL;
        }

        /* add da to list in dm */
        list_add(&da->list, &adev->dm.da_list);

        return da->cpu_ptr;
}

void dm_helpers_free_gpu_mem(
                struct dc_context *ctx,
                enum dc_gpu_mem_alloc_type type,
                void *pvMem)
{
        struct amdgpu_device *adev = ctx->driver_context;
        struct dal_allocation *da;

        /* walk the da list in DM */
        list_for_each_entry(da, &adev->dm.da_list, list) {
                if (pvMem == da->cpu_ptr) {
                        amdgpu_bo_free_kernel(&da->bo, &da->gpu_addr, &da->cpu_ptr);
                        list_del(&da->list);
                        kfree(da);
                        break;
                }
        }
}

bool dm_helpers_dmub_outbox_interrupt_control(struct dc_context *ctx, bool enable)
{
        enum dc_irq_source irq_source;
        bool ret;

        irq_source = DC_IRQ_SOURCE_DMCUB_OUTBOX;

        ret = dc_interrupt_set(ctx->dc, irq_source, enable);

        DRM_DEBUG_DRIVER("Dmub trace irq %sabling: r=%d\n",
                         enable ? "en" : "dis", ret);
        return ret;
}

void dm_helpers_mst_enable_stream_features(const struct dc_stream_state *stream)
{
        /* TODO: virtual DPCD */
        struct dc_link *link = stream->link;
        union down_spread_ctrl old_downspread;
        union down_spread_ctrl new_downspread;

        if (link->aux_access_disabled)
                return;

        if (!dm_helpers_dp_read_dpcd(link->ctx, link, DP_DOWNSPREAD_CTRL,
                                     &old_downspread.raw,
                                     sizeof(old_downspread)))
                return;

        new_downspread.raw = old_downspread.raw;
        new_downspread.bits.IGNORE_MSA_TIMING_PARAM =
                (stream->ignore_msa_timing_param) ? 1 : 0;

        if (new_downspread.raw != old_downspread.raw)
                dm_helpers_dp_write_dpcd(link->ctx, link, DP_DOWNSPREAD_CTRL,
                                         &new_downspread.raw,
                                         sizeof(new_downspread));
}