// SPDX-License-Identifier: MIT
/*
 * Copyright 2021 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 "dc.h"
#include "dc_link_dpia.h"
#include "inc/core_status.h"
#include "dc_link.h"
#include "dc_link_dp.h"
#include "dpcd_defs.h"
#include "link_hwss.h"
#include "dm_helpers.h"
#include "dmub/inc/dmub_cmd.h"
#include "inc/link_dpcd.h"
#include "dc_dmub_srv.h"

#define DC_LOGGER \
        link->ctx->logger

enum dc_status dpcd_get_tunneling_device_data(struct dc_link *link)
{
        enum dc_status status = DC_OK;
        uint8_t dpcd_dp_tun_data[3] = {0};
        uint8_t dpcd_topology_data[DPCD_USB4_TOPOLOGY_ID_LEN] = {0};
        uint8_t i = 0;

        status = core_link_read_dpcd(link,
                        DP_TUNNELING_CAPABILITIES_SUPPORT,
                        dpcd_dp_tun_data,
                        sizeof(dpcd_dp_tun_data));

        status = core_link_read_dpcd(link,
                        DP_USB4_ROUTER_TOPOLOGY_ID,
                        dpcd_topology_data,
                        sizeof(dpcd_topology_data));

        link->dpcd_caps.usb4_dp_tun_info.dp_tun_cap.raw =
                        dpcd_dp_tun_data[DP_TUNNELING_CAPABILITIES_SUPPORT -
                                         DP_TUNNELING_CAPABILITIES_SUPPORT];
        link->dpcd_caps.usb4_dp_tun_info.dpia_info.raw =
                        dpcd_dp_tun_data[DP_IN_ADAPTER_INFO - DP_TUNNELING_CAPABILITIES_SUPPORT];
        link->dpcd_caps.usb4_dp_tun_info.usb4_driver_id =
                        dpcd_dp_tun_data[DP_USB4_DRIVER_ID - DP_TUNNELING_CAPABILITIES_SUPPORT];

        for (i = 0; i < DPCD_USB4_TOPOLOGY_ID_LEN; i++)
                link->dpcd_caps.usb4_dp_tun_info.usb4_topology_id[i] = dpcd_topology_data[i];

        return status;
}

bool dc_link_dpia_query_hpd_status(struct dc_link *link)
{
        union dmub_rb_cmd cmd = {0};
        struct dc_dmub_srv *dmub_srv = link->ctx->dmub_srv;
        bool is_hpd_high = false;

        /* prepare QUERY_HPD command */
        cmd.query_hpd.header.type = DMUB_CMD__QUERY_HPD_STATE;
        cmd.query_hpd.data.instance = link->link_id.enum_id - ENUM_ID_1;
        cmd.query_hpd.data.ch_type = AUX_CHANNEL_DPIA;

        /* Return HPD status reported by DMUB if query successfully executed. */
        if (dc_dmub_srv_cmd_with_reply_data(dmub_srv, &cmd) && cmd.query_hpd.data.status == AUX_RET_SUCCESS)
                is_hpd_high = cmd.query_hpd.data.result;

        return is_hpd_high;
}

/* Configure link as prescribed in link_setting; set LTTPR mode; and
 * Initialize link training settings.
 * Abort link training if sink unplug detected.
 *
 * @param link DPIA link being trained.
 * @param[in] link_setting Lane count, link rate and downspread control.
 * @param[out] lt_settings Link settings and drive settings (voltage swing and pre-emphasis).
 */
static enum link_training_result dpia_configure_link(
                struct dc_link *link,
                const struct link_resource *link_res,
                const struct dc_link_settings *link_setting,
                struct link_training_settings *lt_settings)
{
        enum dc_status status;
        bool fec_enable;

        DC_LOG_HW_LINK_TRAINING("%s\n DPIA(%d) configuring\n - LTTPR mode(%d)\n",
                                __func__,
                                link->link_id.enum_id - ENUM_ID_1,
                                link->lttpr_mode);

        dp_decide_training_settings(link,
                link_setting,
                lt_settings);

        status = dpcd_configure_channel_coding(link, lt_settings);
        if (status != DC_OK && link->is_hpd_pending)
                return LINK_TRAINING_ABORT;

        /* Configure lttpr mode */
        status = dpcd_configure_lttpr_mode(link, lt_settings);
        if (status != DC_OK && link->is_hpd_pending)
                return LINK_TRAINING_ABORT;

        /* Set link rate, lane count and spread. */
        status = dpcd_set_link_settings(link, lt_settings);
        if (status != DC_OK && link->is_hpd_pending)
                return LINK_TRAINING_ABORT;

        if (link->preferred_training_settings.fec_enable)
                fec_enable = *link->preferred_training_settings.fec_enable;
        else
                fec_enable = true;
        status = dp_set_fec_ready(link, link_res, fec_enable);
        if (status != DC_OK && link->is_hpd_pending)
                return LINK_TRAINING_ABORT;

        return LINK_TRAINING_SUCCESS;
}

static enum dc_status core_link_send_set_config(struct dc_link *link,
        uint8_t msg_type,
        uint8_t msg_data)
{
        struct set_config_cmd_payload payload;
        enum set_config_status set_config_result = SET_CONFIG_PENDING;

        /* prepare set_config payload */
        payload.msg_type = msg_type;
        payload.msg_data = msg_data;

        if (!link->ddc->ddc_pin && !link->aux_access_disabled &&
            (dm_helpers_dmub_set_config_sync(link->ctx, link,
                                             &payload, &set_config_result) == -1)) {
                return DC_ERROR_UNEXPECTED;
        }

        /* set_config should return ACK if successful */
        return (set_config_result == SET_CONFIG_ACK_RECEIVED) ? DC_OK : DC_ERROR_UNEXPECTED;
}

/* Build SET_CONFIG message data payload for specified message type. */
static uint8_t dpia_build_set_config_data(enum dpia_set_config_type type,
                struct dc_link *link,
                struct link_training_settings *lt_settings)
{
        union dpia_set_config_data data;

        data.raw = 0;

        switch (type) {
        case DPIA_SET_CFG_SET_LINK:
                data.set_link.mode = link->lttpr_mode == LTTPR_MODE_NON_TRANSPARENT ? 1 : 0;
                break;
        case DPIA_SET_CFG_SET_PHY_TEST_MODE:
                break;
        case DPIA_SET_CFG_SET_VSPE:
                /* Assume all lanes have same drive settings. */
                data.set_vspe.swing = lt_settings->lane_settings[0].VOLTAGE_SWING;
                data.set_vspe.pre_emph = lt_settings->lane_settings[0].PRE_EMPHASIS;
                data.set_vspe.max_swing_reached =
                        lt_settings->lane_settings[0].VOLTAGE_SWING ==
                        VOLTAGE_SWING_MAX_LEVEL ? 1 : 0;
                data.set_vspe.max_pre_emph_reached =
                        lt_settings->lane_settings[0].PRE_EMPHASIS ==
                        PRE_EMPHASIS_MAX_LEVEL ? 1 : 0;
                break;
        default:
                ASSERT(false); /* Message type not supported by helper function. */
                break;
        }

        return data.raw;
}

/* Convert DC training pattern to DPIA training stage. */
static enum dpia_set_config_ts convert_trng_ptn_to_trng_stg(enum dc_dp_training_pattern tps)
{
        enum dpia_set_config_ts ts;

        switch (tps) {
        case DP_TRAINING_PATTERN_SEQUENCE_1:
                ts = DPIA_TS_TPS1;
                break;
        case DP_TRAINING_PATTERN_SEQUENCE_2:
                ts = DPIA_TS_TPS2;
                break;
        case DP_TRAINING_PATTERN_SEQUENCE_3:
                ts = DPIA_TS_TPS3;
                break;
        case DP_TRAINING_PATTERN_SEQUENCE_4:
                ts = DPIA_TS_TPS4;
                break;
        default:
                ts = DPIA_TS_DPRX_DONE;
                ASSERT(false); /* TPS not supported by helper function. */
                break;
        }

        return ts;
}

/* Write training pattern to DPCD. */
static enum dc_status dpcd_set_lt_pattern(struct dc_link *link,
        enum dc_dp_training_pattern pattern,
        uint32_t hop)
{
        union dpcd_training_pattern dpcd_pattern = { {0} };
        uint32_t dpcd_tps_offset = DP_TRAINING_PATTERN_SET;
        enum dc_status status;

        if (hop != DPRX)
                dpcd_tps_offset = DP_TRAINING_PATTERN_SET_PHY_REPEATER1 +
                        ((DP_REPEATER_CONFIGURATION_AND_STATUS_SIZE) * (hop - 1));

        /* DpcdAddress_TrainingPatternSet */
        dpcd_pattern.v1_4.TRAINING_PATTERN_SET =
                dc_dp_training_pattern_to_dpcd_training_pattern(link, pattern);

        dpcd_pattern.v1_4.SCRAMBLING_DISABLE =
                dc_dp_initialize_scrambling_data_symbols(link, pattern);

        if (hop != DPRX) {
                DC_LOG_HW_LINK_TRAINING("%s\n LTTPR Repeater ID: %d\n 0x%X pattern = %x\n",
                                        __func__,
                                        hop,
                                        dpcd_tps_offset,
                                        dpcd_pattern.v1_4.TRAINING_PATTERN_SET);
        } else {
                DC_LOG_HW_LINK_TRAINING("%s\n 0x%X pattern = %x\n",
                                        __func__,
                                        dpcd_tps_offset,
                                        dpcd_pattern.v1_4.TRAINING_PATTERN_SET);
        }

        status = core_link_write_dpcd(link,
                                      dpcd_tps_offset,
                                      &dpcd_pattern.raw,
                                      sizeof(dpcd_pattern.raw));

        return status;
}

/* Execute clock recovery phase of link training for specified hop in display
 * path.in non-transparent mode:
 * - Driver issues both DPCD and SET_CONFIG transactions.
 * - TPS1 is transmitted for any hops downstream of DPOA.
 * - Drive (VS/PE) only transmitted for the hop immediately downstream of DPOA.
 * - CR for the first hop (DPTX-to-DPIA) is assumed to be successful.
 *
 * @param link DPIA link being trained.
 * @param lt_settings link_setting and drive settings (voltage swing and pre-emphasis).
 * @param hop The Hop in display path. DPRX = 0.
 */
static enum link_training_result dpia_training_cr_non_transparent(
                struct dc_link *link,
                const struct link_resource *link_res,
                struct link_training_settings *lt_settings,
                uint32_t hop)
{
        enum link_training_result result = LINK_TRAINING_CR_FAIL_LANE0;
        uint8_t repeater_cnt = 0; /* Number of hops/repeaters in display path. */
        enum dc_status status;
        uint32_t retries_cr = 0; /* Number of consecutive attempts with same VS or PE. */
        uint32_t retry_count = 0;
        /* From DP spec, CR read interval is always 100us. */
        uint32_t wait_time_microsec = TRAINING_AUX_RD_INTERVAL;
        enum dc_lane_count lane_count = lt_settings->link_settings.lane_count;
        union lane_status dpcd_lane_status[LANE_COUNT_DP_MAX] = { { {0} } };
        union lane_align_status_updated dpcd_lane_status_updated = { {0} };
        union lane_adjust dpcd_lane_adjust[LANE_COUNT_DP_MAX] = { { {0} } };
        uint8_t set_cfg_data;
        enum dpia_set_config_ts ts;

        repeater_cnt = dp_convert_to_count(link->dpcd_caps.lttpr_caps.phy_repeater_cnt);

        /* Cap of LINK_TRAINING_MAX_CR_RETRY attempts at clock recovery.
         * Fix inherited from perform_clock_recovery_sequence() -
         * the DP equivalent of this function:
         * Required for Synaptics MST hub which can put the LT in
         * infinite loop by switching the VS between level 0 and level 1
         * continuously.
         */
        while ((retries_cr < LINK_TRAINING_MAX_RETRY_COUNT) &&
               (retry_count < LINK_TRAINING_MAX_CR_RETRY)) {
                /* DPTX-to-DPIA */
                if (hop == repeater_cnt) {
                        /* Send SET_CONFIG(SET_LINK:LC,LR,LTTPR) to notify DPOA that
                         * non-transparent link training has started.
                         * This also enables the transmission of clk_sync packets.
                         */
                        set_cfg_data = dpia_build_set_config_data(DPIA_SET_CFG_SET_LINK,
                                        link,
                                        lt_settings);
                        status = core_link_send_set_config(link,
                                        DPIA_SET_CFG_SET_LINK,
                                        set_cfg_data);
                        /* CR for this hop is considered successful as long as
                         * SET_CONFIG message is acknowledged by DPOA.
                         */
                        if (status == DC_OK)
                                result = LINK_TRAINING_SUCCESS;
                        else
                                result = LINK_TRAINING_ABORT;
                        break;
                }

                /* DPOA-to-x */
                /* Instruct DPOA to transmit TPS1 then update DPCD. */
                if (retry_count == 0) {
                        ts = convert_trng_ptn_to_trng_stg(lt_settings->pattern_for_cr);
                        status = core_link_send_set_config(link,
                                        DPIA_SET_CFG_SET_TRAINING,
                                        ts);
                        if (status != DC_OK) {
                                result = LINK_TRAINING_ABORT;
                                break;
                        }
                        status = dpcd_set_lt_pattern(link, lt_settings->pattern_for_cr, hop);
                        if (status != DC_OK) {
                                result = LINK_TRAINING_ABORT;
                                break;
                        }
                }

                /* Update DPOA drive settings then DPCD. DPOA does only adjusts
                 * drive settings for hops immediately downstream.
                 */
                if (hop == repeater_cnt - 1) {
                        set_cfg_data = dpia_build_set_config_data(DPIA_SET_CFG_SET_VSPE,
                                        link,
                                        lt_settings);
                        status = core_link_send_set_config(link,
                                        DPIA_SET_CFG_SET_VSPE,
                                        set_cfg_data);
                        if (status != DC_OK) {
                                result = LINK_TRAINING_ABORT;
                                break;
                        }
                }
                status = dpcd_set_lane_settings(link, lt_settings, hop);
                if (status != DC_OK) {
                        result = LINK_TRAINING_ABORT;
                        break;
                }

                dp_wait_for_training_aux_rd_interval(link, wait_time_microsec);

                /* Read status and adjustment requests from DPCD. */
                status = dp_get_lane_status_and_lane_adjust(
                                link,
                                lt_settings,
                                dpcd_lane_status,
                                &dpcd_lane_status_updated,
                                dpcd_lane_adjust,
                                hop);
                if (status != DC_OK) {
                        result = LINK_TRAINING_ABORT;
                        break;
                }

                /* Check if clock recovery successful. */
                if (dp_is_cr_done(lane_count, dpcd_lane_status)) {
                        result = LINK_TRAINING_SUCCESS;
                        break;
                }

                result = dp_get_cr_failure(lane_count, dpcd_lane_status);

                if (dp_is_max_vs_reached(lt_settings))
                        break;

                /* Count number of attempts with same drive settings.
                 * Note: settings are the same for all lanes,
                 * so comparing first lane is sufficient.
                 */
                if ((lt_settings->dpcd_lane_settings[0].bits.VOLTAGE_SWING_SET ==
                                dpcd_lane_adjust[0].bits.VOLTAGE_SWING_LANE)
                                && (lt_settings->dpcd_lane_settings[0].bits.PRE_EMPHASIS_SET ==
                                                dpcd_lane_adjust[0].bits.PRE_EMPHASIS_LANE))
                        retries_cr++;
                else
                        retries_cr = 0;

                /* Update VS/PE. */
                dp_decide_lane_settings(lt_settings, dpcd_lane_adjust,
                                lt_settings->lane_settings,
                                lt_settings->dpcd_lane_settings);
                retry_count++;
        }

        /* Abort link training if clock recovery failed due to HPD unplug. */
        if (link->is_hpd_pending)
                result = LINK_TRAINING_ABORT;

        DC_LOG_HW_LINK_TRAINING("%s\n DPIA(%d) clock recovery\n"
                " -hop(%d)\n - result(%d)\n - retries(%d)\n",
                __func__,
                link->link_id.enum_id - ENUM_ID_1,
                hop,
                result,
                retry_count);

        return result;
}

/* Execute clock recovery phase of link training in transparent LTTPR mode:
 * - Driver only issues DPCD transactions and leaves USB4 tunneling (SET_CONFIG) messages to DPIA.
 * - Driver writes TPS1 to DPCD to kick off training.
 * - Clock recovery (CR) for link is handled by DPOA, which reports result to DPIA on completion.
 * - DPIA communicates result to driver by updating CR status when driver reads DPCD.
 *
 * @param link DPIA link being trained.
 * @param lt_settings link_setting and drive settings (voltage swing and pre-emphasis).
 */
static enum link_training_result dpia_training_cr_transparent(
                struct dc_link *link,
                const struct link_resource *link_res,
                struct link_training_settings *lt_settings)
{
        enum link_training_result result = LINK_TRAINING_CR_FAIL_LANE0;
        enum dc_status status;
        uint32_t retries_cr = 0; /* Number of consecutive attempts with same VS or PE. */
        uint32_t retry_count = 0;
        uint32_t wait_time_microsec = lt_settings->cr_pattern_time;
        enum dc_lane_count lane_count = lt_settings->link_settings.lane_count;
        union lane_status dpcd_lane_status[LANE_COUNT_DP_MAX] = { { {0} } };
        union lane_align_status_updated dpcd_lane_status_updated = { {0} };
        union lane_adjust dpcd_lane_adjust[LANE_COUNT_DP_MAX] = { { {0} } };

        /* Cap of LINK_TRAINING_MAX_CR_RETRY attempts at clock recovery.
         * Fix inherited from perform_clock_recovery_sequence() -
         * the DP equivalent of this function:
         * Required for Synaptics MST hub which can put the LT in
         * infinite loop by switching the VS between level 0 and level 1
         * continuously.
         */
        while ((retries_cr < LINK_TRAINING_MAX_RETRY_COUNT) &&
               (retry_count < LINK_TRAINING_MAX_CR_RETRY)) {
                /* Write TPS1 (not VS or PE) to DPCD to start CR phase.
                 * DPIA sends SET_CONFIG(SET_LINK) to notify DPOA to
                 * start link training.
                 */
                if (retry_count == 0) {
                        status = dpcd_set_lt_pattern(link, lt_settings->pattern_for_cr, DPRX);
                        if (status != DC_OK) {
                                result = LINK_TRAINING_ABORT;
                                break;
                        }
                }

                dp_wait_for_training_aux_rd_interval(link, wait_time_microsec);

                /* Read status and adjustment requests from DPCD. */
                status = dp_get_lane_status_and_lane_adjust(
                                link,
                                lt_settings,
                                dpcd_lane_status,
                                &dpcd_lane_status_updated,
                                dpcd_lane_adjust,
                                DPRX);
                if (status != DC_OK) {
                        result = LINK_TRAINING_ABORT;
                        break;
                }

                /* Check if clock recovery successful. */
                if (dp_is_cr_done(lane_count, dpcd_lane_status)) {
                        result = LINK_TRAINING_SUCCESS;
                        break;
                }

                result = dp_get_cr_failure(lane_count, dpcd_lane_status);

                if (dp_is_max_vs_reached(lt_settings))
                        break;

                /* Count number of attempts with same drive settings.
                 * Note: settings are the same for all lanes,
                 * so comparing first lane is sufficient.
                 */
                if ((lt_settings->dpcd_lane_settings[0].bits.VOLTAGE_SWING_SET ==
                                dpcd_lane_adjust[0].bits.VOLTAGE_SWING_LANE)
                                && (lt_settings->dpcd_lane_settings[0].bits.PRE_EMPHASIS_SET ==
                                                dpcd_lane_adjust[0].bits.PRE_EMPHASIS_LANE))
                        retries_cr++;
                else
                        retries_cr = 0;

                /* Update VS/PE. */
                dp_decide_lane_settings(lt_settings, dpcd_lane_adjust,
                                lt_settings->hw_lane_settings, lt_settings->dpcd_lane_settings);
                retry_count++;
        }

        /* Abort link training if clock recovery failed due to HPD unplug. */
        if (link->is_hpd_pending)
                result = LINK_TRAINING_ABORT;

        DC_LOG_HW_LINK_TRAINING("%s\n DPIA(%d) clock recovery\n"
                " -hop(%d)\n - result(%d)\n - retries(%d)\n",
                __func__,
                link->link_id.enum_id - ENUM_ID_1,
                DPRX,
                result,
                retry_count);

        return result;
}

/* Execute clock recovery phase of link training for specified hop in display
 * path.
 *
 * @param link DPIA link being trained.
 * @param lt_settings link_setting and drive settings (voltage swing and pre-emphasis).
 * @param hop The Hop in display path. DPRX = 0.
 */
static enum link_training_result dpia_training_cr_phase(
                struct dc_link *link,
                const struct link_resource *link_res,
                struct link_training_settings *lt_settings,
                uint32_t hop)
{
        enum link_training_result result = LINK_TRAINING_CR_FAIL_LANE0;

        if (link->lttpr_mode == LTTPR_MODE_NON_TRANSPARENT)
                result = dpia_training_cr_non_transparent(link, link_res, lt_settings, hop);
        else
                result = dpia_training_cr_transparent(link, link_res, lt_settings);

        return result;
}

/* Return status read interval during equalization phase. */
static uint32_t dpia_get_eq_aux_rd_interval(const struct dc_link *link,
                const struct link_training_settings *lt_settings,
                uint32_t hop)
{
        uint32_t wait_time_microsec;

        if (hop == DPRX)
                wait_time_microsec = lt_settings->eq_pattern_time;
        else
                wait_time_microsec =
                                dp_translate_training_aux_read_interval(
                                        link->dpcd_caps.lttpr_caps.aux_rd_interval[hop - 1]);

        /* Check debug option for extending aux read interval. */
        if (link->dc->debug.dpia_debug.bits.extend_aux_rd_interval)
                wait_time_microsec = DPIA_DEBUG_EXTENDED_AUX_RD_INTERVAL_US;

        return wait_time_microsec;
}

/* Execute equalization phase of link training for specified hop in display
 * path in non-transparent mode:
 * - driver issues both DPCD and SET_CONFIG transactions.
 * - TPSx is transmitted for any hops downstream of DPOA.
 * - Drive (VS/PE) only transmitted for the hop immediately downstream of DPOA.
 * - EQ for the first hop (DPTX-to-DPIA) is assumed to be successful.
 * - DPRX EQ only reported successful when both DPRX and DPIA requirements
 * (clk sync packets sent) fulfilled.
 *
 * @param link DPIA link being trained.
 * @param lt_settings link_setting and drive settings (voltage swing and pre-emphasis).
 * @param hop The Hop in display path. DPRX = 0.
 */
static enum link_training_result dpia_training_eq_non_transparent(
                struct dc_link *link,
                const struct link_resource *link_res,
                struct link_training_settings *lt_settings,
                uint32_t hop)
{
        enum link_training_result result = LINK_TRAINING_EQ_FAIL_EQ;
        uint8_t repeater_cnt = 0; /* Number of hops/repeaters in display path. */
        uint32_t retries_eq = 0;
        enum dc_status status;
        enum dc_dp_training_pattern tr_pattern;
        uint32_t wait_time_microsec;
        enum dc_lane_count lane_count = lt_settings->link_settings.lane_count;
        union lane_align_status_updated dpcd_lane_status_updated = { {0} };
        union lane_status dpcd_lane_status[LANE_COUNT_DP_MAX] = { { {0} } };
        union lane_adjust dpcd_lane_adjust[LANE_COUNT_DP_MAX] = { { {0} } };
        uint8_t set_cfg_data;
        enum dpia_set_config_ts ts;

        /* Training pattern is TPS4 for repeater;
         * TPS2/3/4 for DPRX depending on what it supports.
         */
        if (hop == DPRX)
                tr_pattern = lt_settings->pattern_for_eq;
        else
                tr_pattern = DP_TRAINING_PATTERN_SEQUENCE_4;

        repeater_cnt = dp_convert_to_count(link->dpcd_caps.lttpr_caps.phy_repeater_cnt);

        for (retries_eq = 0; retries_eq < LINK_TRAINING_MAX_RETRY_COUNT; retries_eq++) {
                /* DPTX-to-DPIA equalization always successful. */
                if (hop == repeater_cnt) {
                        result = LINK_TRAINING_SUCCESS;
                        break;
                }

                /* Instruct DPOA to transmit TPSn then update DPCD. */
                if (retries_eq == 0) {
                        ts = convert_trng_ptn_to_trng_stg(tr_pattern);
                        status = core_link_send_set_config(link,
                                        DPIA_SET_CFG_SET_TRAINING,
                                        ts);
                        if (status != DC_OK) {
                                result = LINK_TRAINING_ABORT;
                                break;
                        }
                        status = dpcd_set_lt_pattern(link, tr_pattern, hop);
                        if (status != DC_OK) {
                                result = LINK_TRAINING_ABORT;
                                break;
                        }
                }

                /* Update DPOA drive settings then DPCD. DPOA only adjusts
                 * drive settings for hop immediately downstream.
                 */
                if (hop == repeater_cnt - 1) {
                        set_cfg_data = dpia_build_set_config_data(DPIA_SET_CFG_SET_VSPE,
                                                                  link,
                                                                  lt_settings);
                        status = core_link_send_set_config(link,
                                                           DPIA_SET_CFG_SET_VSPE,
                                                           set_cfg_data);
                        if (status != DC_OK) {
                                result = LINK_TRAINING_ABORT;
                                break;
                        }
                }
                status = dpcd_set_lane_settings(link, lt_settings, hop);
                if (status != DC_OK) {
                        result = LINK_TRAINING_ABORT;
                        break;
                }

                /* Extend wait time on second equalisation attempt on final hop to
                 * ensure clock sync packets have been sent.
                 */
                if (hop == DPRX && retries_eq == 1)
                        wait_time_microsec = max(wait_time_microsec, (uint32_t)DPIA_CLK_SYNC_DELAY);
                else
                        wait_time_microsec = dpia_get_eq_aux_rd_interval(link, lt_settings, hop);

                dp_wait_for_training_aux_rd_interval(link, wait_time_microsec);

                /* Read status and adjustment requests from DPCD. */
                status = dp_get_lane_status_and_lane_adjust(
                                link,
                                lt_settings,
                                dpcd_lane_status,
                                &dpcd_lane_status_updated,
                                dpcd_lane_adjust,
                                hop);
                if (status != DC_OK) {
                        result = LINK_TRAINING_ABORT;
                        break;
                }

                /* CR can still fail during EQ phase. Fail training if CR fails. */
                if (!dp_is_cr_done(lane_count, dpcd_lane_status)) {
                        result = LINK_TRAINING_EQ_FAIL_CR;
                        break;
                }

                if (dp_is_ch_eq_done(lane_count, dpcd_lane_status) &&
                    dp_is_symbol_locked(link->cur_link_settings.lane_count, dpcd_lane_status) &&
                    dp_is_interlane_aligned(dpcd_lane_status_updated)) {
                        result =  LINK_TRAINING_SUCCESS;
                        break;
                }

                /* Update VS/PE. */
                dp_decide_lane_settings(lt_settings, dpcd_lane_adjust,
                                lt_settings->hw_lane_settings, lt_settings->dpcd_lane_settings);
        }

        /* Abort link training if equalization failed due to HPD unplug. */
        if (link->is_hpd_pending)
                result = LINK_TRAINING_ABORT;

        DC_LOG_HW_LINK_TRAINING("%s\n DPIA(%d) equalization\n"
                " - hop(%d)\n - result(%d)\n - retries(%d)\n",
                __func__,
                link->link_id.enum_id - ENUM_ID_1,
                hop,
                result,
                retries_eq);

        return result;
}

/* Execute equalization phase of link training for specified hop in display
 * path in transparent LTTPR mode:
 * - driver only issues DPCD transactions leaves USB4 tunneling (SET_CONFIG) messages to DPIA.
 * - driver writes TPSx to DPCD to notify DPIA that is in equalization phase.
 * - equalization (EQ) for link is handled by DPOA, which reports result to DPIA on completion.
 * - DPIA communicates result to driver by updating EQ status when driver reads DPCD.
 *
 * @param link DPIA link being trained.
 * @param lt_settings link_setting and drive settings (voltage swing and pre-emphasis).
 * @param hop The Hop in display path. DPRX = 0.
 */
static enum link_training_result dpia_training_eq_transparent(
                struct dc_link *link,
                const struct link_resource *link_res,
                struct link_training_settings *lt_settings)
{
        enum link_training_result result = LINK_TRAINING_EQ_FAIL_EQ;
        uint32_t retries_eq = 0;
        enum dc_status status;
        enum dc_dp_training_pattern tr_pattern = lt_settings->pattern_for_eq;
        uint32_t wait_time_microsec;
        enum dc_lane_count lane_count = lt_settings->link_settings.lane_count;
        union lane_align_status_updated dpcd_lane_status_updated = { {0} };
        union lane_status dpcd_lane_status[LANE_COUNT_DP_MAX] = { { {0} } };
        union lane_adjust dpcd_lane_adjust[LANE_COUNT_DP_MAX] = { { {0} } };

        wait_time_microsec = dpia_get_eq_aux_rd_interval(link, lt_settings, DPRX);

        for (retries_eq = 0; retries_eq < LINK_TRAINING_MAX_RETRY_COUNT; retries_eq++) {
                if (retries_eq == 0) {
                        status = dpcd_set_lt_pattern(link, tr_pattern, DPRX);
                        if (status != DC_OK) {
                                result = LINK_TRAINING_ABORT;
                                break;
                        }
                }

                dp_wait_for_training_aux_rd_interval(link, wait_time_microsec);

                /* Read status and adjustment requests from DPCD. */
                status = dp_get_lane_status_and_lane_adjust(
                                link,
                                lt_settings,
                                dpcd_lane_status,
                                &dpcd_lane_status_updated,
                                dpcd_lane_adjust,
                                DPRX);
                if (status != DC_OK) {
                        result = LINK_TRAINING_ABORT;
                        break;
                }

                /* CR can still fail during EQ phase. Fail training if CR fails. */
                if (!dp_is_cr_done(lane_count, dpcd_lane_status)) {
                        result = LINK_TRAINING_EQ_FAIL_CR;
                        break;
                }

                if (dp_is_ch_eq_done(lane_count, dpcd_lane_status) &&
                    dp_is_symbol_locked(link->cur_link_settings.lane_count, dpcd_lane_status) &&
                    dp_is_interlane_aligned(dpcd_lane_status_updated)) {
                        result =  LINK_TRAINING_SUCCESS;
                        break;
                }

                /* Update VS/PE. */
                dp_decide_lane_settings(lt_settings, dpcd_lane_adjust,
                                lt_settings->hw_lane_settings, lt_settings->dpcd_lane_settings);
        }

        /* Abort link training if equalization failed due to HPD unplug. */
        if (link->is_hpd_pending)
                result = LINK_TRAINING_ABORT;

        DC_LOG_HW_LINK_TRAINING("%s\n DPIA(%d) equalization\n"
                " - hop(%d)\n - result(%d)\n - retries(%d)\n",
                __func__,
                link->link_id.enum_id - ENUM_ID_1,
                DPRX,
                result,
                retries_eq);

        return result;
}

/* Execute equalization phase of link training for specified hop in display
 * path.
 *
 * @param link DPIA link being trained.
 * @param lt_settings link_setting and drive settings (voltage swing and pre-emphasis).
 * @param hop The Hop in display path. DPRX = 0.
 */
static enum link_training_result dpia_training_eq_phase(
                struct dc_link *link,
                const struct link_resource *link_res,
                struct link_training_settings *lt_settings,
                uint32_t hop)
{
        enum link_training_result result;

        if (link->lttpr_mode == LTTPR_MODE_NON_TRANSPARENT)
                result = dpia_training_eq_non_transparent(link, link_res, lt_settings, hop);
        else
                result = dpia_training_eq_transparent(link, link_res, lt_settings);

        return result;
}

/* End training of specified hop in display path. */
static enum dc_status dpcd_clear_lt_pattern(struct dc_link *link, uint32_t hop)
{
        union dpcd_training_pattern dpcd_pattern = { {0} };
        uint32_t dpcd_tps_offset = DP_TRAINING_PATTERN_SET;
        enum dc_status status;

        if (hop != DPRX)
                dpcd_tps_offset = DP_TRAINING_PATTERN_SET_PHY_REPEATER1 +
                        ((DP_REPEATER_CONFIGURATION_AND_STATUS_SIZE) * (hop - 1));

        status = core_link_write_dpcd(link,
                        dpcd_tps_offset,
                        &dpcd_pattern.raw,
                        sizeof(dpcd_pattern.raw));

        return status;
}

/* End training of specified hop in display path.
 *
 * In transparent LTTPR mode:
 * - driver clears training pattern for the specified hop in DPCD.
 * In non-transparent LTTPR mode:
 * - in addition to clearing training pattern, driver issues USB4 tunneling
 * (SET_CONFIG) messages to notify DPOA when training is done for first hop
 * (DPTX-to-DPIA) and last hop (DPRX).
 *
 * @param link DPIA link being trained.
 * @param hop The Hop in display path. DPRX = 0.
 */
static enum link_training_result dpia_training_end(struct dc_link *link,
                uint32_t hop)
{
        enum link_training_result result = LINK_TRAINING_SUCCESS;
        uint8_t repeater_cnt = 0; /* Number of hops/repeaters in display path. */
        enum dc_status status;

        if (link->lttpr_mode == LTTPR_MODE_NON_TRANSPARENT) {
                repeater_cnt = dp_convert_to_count(link->dpcd_caps.lttpr_caps.phy_repeater_cnt);

                if (hop == repeater_cnt) { /* DPTX-to-DPIA */
                        /* Send SET_CONFIG(SET_TRAINING:0xff) to notify DPOA that
                         * DPTX-to-DPIA hop trained. No DPCD write needed for first hop.
                         */
                        status = core_link_send_set_config(link,
                                        DPIA_SET_CFG_SET_TRAINING,
                                        DPIA_TS_UFP_DONE);
                        if (status != DC_OK)
                                result = LINK_TRAINING_ABORT;
                } else { /* DPOA-to-x */
                        /* Write 0x0 to TRAINING_PATTERN_SET */
                        status = dpcd_clear_lt_pattern(link, hop);
                        if (status != DC_OK)
                                result = LINK_TRAINING_ABORT;
                }

                /* Notify DPOA that non-transparent link training of DPRX done. */
                if (hop == DPRX && result != LINK_TRAINING_ABORT) {
                        status = core_link_send_set_config(link,
                                        DPIA_SET_CFG_SET_TRAINING,
                                        DPIA_TS_DPRX_DONE);
                        if (status != DC_OK)
                                result = LINK_TRAINING_ABORT;
                }

        } else { /* non-LTTPR or transparent LTTPR. */
                /* Write 0x0 to TRAINING_PATTERN_SET */
                status = dpcd_clear_lt_pattern(link, hop);
                if (status != DC_OK)
                        result = LINK_TRAINING_ABORT;
        }

        DC_LOG_HW_LINK_TRAINING("%s\n DPIA(%d) end\n - hop(%d)\n - result(%d)\n - LTTPR mode(%d)\n",
                                __func__,
                                link->link_id.enum_id - ENUM_ID_1,
                                hop,
                                result,
                                link->lttpr_mode);

        return result;
}

/* When aborting training of specified hop in display path, clean up by:
 * - Attempting to clear DPCD TRAINING_PATTERN_SET, LINK_BW_SET and LANE_COUNT_SET.
 * - Sending SET_CONFIG(SET_LINK) with lane count and link rate set to 0.
 *
 * @param link DPIA link being trained.
 * @param hop The Hop in display path. DPRX = 0.
 */
static void dpia_training_abort(struct dc_link *link, uint32_t hop)
{
        uint8_t data = 0;
        uint32_t dpcd_tps_offset = DP_TRAINING_PATTERN_SET;

        DC_LOG_HW_LINK_TRAINING("%s\n DPIA(%d) aborting\n - LTTPR mode(%d)\n - HPD(%d)\n",
                                __func__,
                                link->link_id.enum_id - ENUM_ID_1,
                                link->lttpr_mode,
                                link->is_hpd_pending);

        /* Abandon clean-up if sink unplugged. */
        if (link->is_hpd_pending)
                return;

        if (hop != DPRX)
                dpcd_tps_offset = DP_TRAINING_PATTERN_SET_PHY_REPEATER1 +
                        ((DP_REPEATER_CONFIGURATION_AND_STATUS_SIZE) * (hop - 1));

        core_link_write_dpcd(link, dpcd_tps_offset, &data, 1);
        core_link_write_dpcd(link, DP_LINK_BW_SET, &data, 1);
        core_link_write_dpcd(link, DP_LANE_COUNT_SET, &data, 1);
        core_link_send_set_config(link, DPIA_SET_CFG_SET_LINK, data);
}

enum link_training_result dc_link_dpia_perform_link_training(
        struct dc_link *link,
        const struct link_resource *link_res,
        const struct dc_link_settings *link_setting,
        bool skip_video_pattern)
{
        enum link_training_result result;
        struct link_training_settings lt_settings;
        uint8_t repeater_cnt = 0; /* Number of hops/repeaters in display path. */
        int8_t repeater_id; /* Current hop. */

        /* Configure link as prescribed in link_setting and set LTTPR mode. */
        result = dpia_configure_link(link, link_res, link_setting, &lt_settings);
        if (result != LINK_TRAINING_SUCCESS)
                return result;

        if (link->lttpr_mode == LTTPR_MODE_NON_TRANSPARENT)
                repeater_cnt = dp_convert_to_count(link->dpcd_caps.lttpr_caps.phy_repeater_cnt);

        /* Train each hop in turn starting with the one closest to DPTX.
         * In transparent or non-LTTPR mode, train only the final hop (DPRX).
         */
        for (repeater_id = repeater_cnt; repeater_id >= 0; repeater_id--) {
                /* Clock recovery. */
                result = dpia_training_cr_phase(link, link_res, &lt_settings, repeater_id);
                if (result != LINK_TRAINING_SUCCESS)
                        break;

                /* Equalization. */
                result = dpia_training_eq_phase(link, link_res, &lt_settings, repeater_id);
                if (result != LINK_TRAINING_SUCCESS)
                        break;

                /* Stop training hop. */
                result = dpia_training_end(link, repeater_id);
                if (result != LINK_TRAINING_SUCCESS)
                        break;
        }

        /* Double-check link status if training successful; gracefully abort
         * training of current hop if training failed due to message tunneling
         * failure; end training of hop if training ended conventionally and
         * falling back to lower bandwidth settings possible.
         */
        if (result == LINK_TRAINING_SUCCESS) {
                msleep(5);
                result = dp_check_link_loss_status(link, &lt_settings);
        } else if (result == LINK_TRAINING_ABORT) {
                dpia_training_abort(link, repeater_id);
        } else {
                dpia_training_end(link, repeater_id);
        }
        return result;
}