xref: /kernel/linux/linux-5.10/drivers/gpu/drm/amd/amdgpu/atombios_dp.c

/*
 * Copyright 2007-8 Advanced Micro Devices, Inc.
 * Copyright 2008 Red Hat 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: Dave Airlie
 *          Alex Deucher
 *          Jerome Glisse
 */

#include <drm/amdgpu_drm.h>
#include "amdgpu.h"

#include "atom.h"
#include "atom-bits.h"
#include "atombios_encoders.h"
#include "atombios_dp.h"
#include "amdgpu_connectors.h"
#include "amdgpu_atombios.h"
#include <drm/drm_dp_helper.h>

/* move these to drm_dp_helper.c/h */
#define DP_LINK_CONFIGURATION_SIZE 9
#define DP_DPCD_SIZE DP_RECEIVER_CAP_SIZE

static char *voltage_names[] = {
	"0.4V", "0.6V", "0.8V", "1.2V"
};
static char *pre_emph_names[] = {
	"0dB", "3.5dB", "6dB", "9.5dB"
};

/***** amdgpu AUX functions *****/

union aux_channel_transaction {
	PROCESS_AUX_CHANNEL_TRANSACTION_PS_ALLOCATION v1;
	PROCESS_AUX_CHANNEL_TRANSACTION_PARAMETERS_V2 v2;
};

static int amdgpu_atombios_dp_process_aux_ch(struct amdgpu_i2c_chan *chan,
				      u8 *send, int send_bytes,
				      u8 *recv, int recv_size,
				      u8 delay, u8 *ack)
{
	struct drm_device *dev = chan->dev;
	struct amdgpu_device *adev = drm_to_adev(dev);
	union aux_channel_transaction args;
	int index = GetIndexIntoMasterTable(COMMAND, ProcessAuxChannelTransaction);
	unsigned char *base;
	int recv_bytes;
	int r = 0;

	memset(&args, 0, sizeof(args));

	mutex_lock(&chan->mutex);

	base = (unsigned char *)(adev->mode_info.atom_context->scratch + 1);

	amdgpu_atombios_copy_swap(base, send, send_bytes, true);

	args.v2.lpAuxRequest = cpu_to_le16((u16)(0 + 4));
	args.v2.lpDataOut = cpu_to_le16((u16)(16 + 4));
	args.v2.ucDataOutLen = 0;
	args.v2.ucChannelID = chan->rec.i2c_id;
	args.v2.ucDelay = delay / 10;
	args.v2.ucHPD_ID = chan->rec.hpd;

	amdgpu_atom_execute_table(adev->mode_info.atom_context, index, (uint32_t *)&args);

	*ack = args.v2.ucReplyStatus;

	/* timeout */
	if (args.v2.ucReplyStatus == 1) {
		r = -ETIMEDOUT;
		goto done;
	}

	/* flags not zero */
	if (args.v2.ucReplyStatus == 2) {
		DRM_DEBUG_KMS("dp_aux_ch flags not zero\n");
		r = -EIO;
		goto done;
	}

	/* error */
	if (args.v2.ucReplyStatus == 3) {
		DRM_DEBUG_KMS("dp_aux_ch error\n");
		r = -EIO;
		goto done;
	}

	recv_bytes = args.v1.ucDataOutLen;
	if (recv_bytes > recv_size)
		recv_bytes = recv_size;

	if (recv && recv_size)
		amdgpu_atombios_copy_swap(recv, base + 16, recv_bytes, false);

	r = recv_bytes;
done:
	mutex_unlock(&chan->mutex);

	return r;
}

#define BARE_ADDRESS_SIZE 3
#define HEADER_SIZE (BARE_ADDRESS_SIZE + 1)

static ssize_t
amdgpu_atombios_dp_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
{
	struct amdgpu_i2c_chan *chan =
		container_of(aux, struct amdgpu_i2c_chan, aux);
	int ret;
	u8 tx_buf[20];
	size_t tx_size;
	u8 ack, delay = 0;

	if (WARN_ON(msg->size > 16))
		return -E2BIG;

	tx_buf[0] = msg->address & 0xff;
	tx_buf[1] = msg->address >> 8;
	tx_buf[2] = (msg->request << 4) |
		((msg->address >> 16) & 0xf);
	tx_buf[3] = msg->size ? (msg->size - 1) : 0;

	switch (msg->request & ~DP_AUX_I2C_MOT) {
	case DP_AUX_NATIVE_WRITE:
	case DP_AUX_I2C_WRITE:
		/* tx_size needs to be 4 even for bare address packets since the atom
		 * table needs the info in tx_buf[3].
		 */
		tx_size = HEADER_SIZE + msg->size;
		if (msg->size == 0)
			tx_buf[3] |= BARE_ADDRESS_SIZE << 4;
		else
			tx_buf[3] |= tx_size << 4;
		memcpy(tx_buf + HEADER_SIZE, msg->buffer, msg->size);
		ret = amdgpu_atombios_dp_process_aux_ch(chan,
						 tx_buf, tx_size, NULL, 0, delay, &ack);
		if (ret >= 0)
			/* Return payload size. */
			ret = msg->size;
		break;
	case DP_AUX_NATIVE_READ:
	case DP_AUX_I2C_READ:
		/* tx_size needs to be 4 even for bare address packets since the atom
		 * table needs the info in tx_buf[3].
		 */
		tx_size = HEADER_SIZE;
		if (msg->size == 0)
			tx_buf[3] |= BARE_ADDRESS_SIZE << 4;
		else
			tx_buf[3] |= tx_size << 4;
		ret = amdgpu_atombios_dp_process_aux_ch(chan,
						 tx_buf, tx_size, msg->buffer, msg->size, delay, &ack);
		break;
	default:
		ret = -EINVAL;
		break;
	}

	if (ret >= 0)
		msg->reply = ack >> 4;

	return ret;
}

void amdgpu_atombios_dp_aux_init(struct amdgpu_connector *amdgpu_connector)
{
	amdgpu_connector->ddc_bus->rec.hpd = amdgpu_connector->hpd.hpd;
	amdgpu_connector->ddc_bus->aux.transfer = amdgpu_atombios_dp_aux_transfer;
	drm_dp_aux_init(&amdgpu_connector->ddc_bus->aux);
	amdgpu_connector->ddc_bus->has_aux = true;
}

/***** general DP utility functions *****/

#define DP_VOLTAGE_MAX         DP_TRAIN_VOLTAGE_SWING_LEVEL_3
#define DP_PRE_EMPHASIS_MAX    DP_TRAIN_PRE_EMPH_LEVEL_3

static void amdgpu_atombios_dp_get_adjust_train(const u8 link_status[DP_LINK_STATUS_SIZE],
						int lane_count,
						u8 train_set[4])
{
	u8 v = 0;
	u8 p = 0;
	int lane;

	for (lane = 0; lane < lane_count; lane++) {
		u8 this_v = drm_dp_get_adjust_request_voltage(link_status, lane);
		u8 this_p = drm_dp_get_adjust_request_pre_emphasis(link_status, lane);

		DRM_DEBUG_KMS("requested signal parameters: lane %d voltage %s pre_emph %s\n",
			  lane,
			  voltage_names[this_v >> DP_TRAIN_VOLTAGE_SWING_SHIFT],
			  pre_emph_names[this_p >> DP_TRAIN_PRE_EMPHASIS_SHIFT]);

		if (this_v > v)
			v = this_v;
		if (this_p > p)
			p = this_p;
	}

	if (v >= DP_VOLTAGE_MAX)
		v |= DP_TRAIN_MAX_SWING_REACHED;

	if (p >= DP_PRE_EMPHASIS_MAX)
		p |= DP_TRAIN_MAX_PRE_EMPHASIS_REACHED;

	DRM_DEBUG_KMS("using signal parameters: voltage %s pre_emph %s\n",
		  voltage_names[(v & DP_TRAIN_VOLTAGE_SWING_MASK) >> DP_TRAIN_VOLTAGE_SWING_SHIFT],
		  pre_emph_names[(p & DP_TRAIN_PRE_EMPHASIS_MASK) >> DP_TRAIN_PRE_EMPHASIS_SHIFT]);

	for (lane = 0; lane < 4; lane++)
		train_set[lane] = v | p;
}

/* convert bits per color to bits per pixel */
/* get bpc from the EDID */
static unsigned amdgpu_atombios_dp_convert_bpc_to_bpp(int bpc)
{
	if (bpc == 0)
		return 24;
	else
		return bpc * 3;
}

/***** amdgpu specific DP functions *****/

static int amdgpu_atombios_dp_get_dp_link_config(struct drm_connector *connector,
						 const u8 dpcd[DP_DPCD_SIZE],
						 unsigned pix_clock,
						 unsigned *dp_lanes, unsigned *dp_rate)
{
	unsigned bpp =
		amdgpu_atombios_dp_convert_bpc_to_bpp(amdgpu_connector_get_monitor_bpc(connector));
	static const unsigned link_rates[3] = { 162000, 270000, 540000 };
	unsigned max_link_rate = drm_dp_max_link_rate(dpcd);
	unsigned max_lane_num = drm_dp_max_lane_count(dpcd);
	unsigned lane_num, i, max_pix_clock;

	if (amdgpu_connector_encoder_get_dp_bridge_encoder_id(connector) ==
	    ENCODER_OBJECT_ID_NUTMEG) {
		for (lane_num = 1; lane_num <= max_lane_num; lane_num <<= 1) {
			max_pix_clock = (lane_num * 270000 * 8) / bpp;
			if (max_pix_clock >= pix_clock) {
				*dp_lanes = lane_num;
				*dp_rate = 270000;
				return 0;
			}
		}
	} else {
		for (i = 0; i < ARRAY_SIZE(link_rates) && link_rates[i] <= max_link_rate; i++) {
			for (lane_num = 1; lane_num <= max_lane_num; lane_num <<= 1) {
				max_pix_clock = (lane_num * link_rates[i] * 8) / bpp;
				if (max_pix_clock >= pix_clock) {
					*dp_lanes = lane_num;
					*dp_rate = link_rates[i];
					return 0;
				}
			}
		}
	}

	return -EINVAL;
}

static u8 amdgpu_atombios_dp_encoder_service(struct amdgpu_device *adev,
				      int action, int dp_clock,
				      u8 ucconfig, u8 lane_num)
{
	DP_ENCODER_SERVICE_PARAMETERS args;
	int index = GetIndexIntoMasterTable(COMMAND, DPEncoderService);

	memset(&args, 0, sizeof(args));
	args.ucLinkClock = dp_clock / 10;
	args.ucConfig = ucconfig;
	args.ucAction = action;
	args.ucLaneNum = lane_num;
	args.ucStatus = 0;

	amdgpu_atom_execute_table(adev->mode_info.atom_context, index, (uint32_t *)&args);
	return args.ucStatus;
}

u8 amdgpu_atombios_dp_get_sinktype(struct amdgpu_connector *amdgpu_connector)
{
	struct drm_device *dev = amdgpu_connector->base.dev;
	struct amdgpu_device *adev = drm_to_adev(dev);

	return amdgpu_atombios_dp_encoder_service(adev, ATOM_DP_ACTION_GET_SINK_TYPE, 0,
					   amdgpu_connector->ddc_bus->rec.i2c_id, 0);
}

static void amdgpu_atombios_dp_probe_oui(struct amdgpu_connector *amdgpu_connector)
{
	struct amdgpu_connector_atom_dig *dig_connector = amdgpu_connector->con_priv;
	u8 buf[3];

	if (!(dig_connector->dpcd[DP_DOWN_STREAM_PORT_COUNT] & DP_OUI_SUPPORT))
		return;

	if (drm_dp_dpcd_read(&amdgpu_connector->ddc_bus->aux, DP_SINK_OUI, buf, 3) == 3)
		DRM_DEBUG_KMS("Sink OUI: %02hx%02hx%02hx\n",
			      buf[0], buf[1], buf[2]);

	if (drm_dp_dpcd_read(&amdgpu_connector->ddc_bus->aux, DP_BRANCH_OUI, buf, 3) == 3)
		DRM_DEBUG_KMS("Branch OUI: %02hx%02hx%02hx\n",
			      buf[0], buf[1], buf[2]);
}

static void amdgpu_atombios_dp_ds_ports(struct amdgpu_connector *amdgpu_connector)
{
	struct amdgpu_connector_atom_dig *dig_connector = amdgpu_connector->con_priv;
	int ret;

	if (dig_connector->dpcd[DP_DPCD_REV] > 0x10) {
		ret = drm_dp_dpcd_read(&amdgpu_connector->ddc_bus->aux,
				       DP_DOWNSTREAM_PORT_0,
				       dig_connector->downstream_ports,
				       DP_MAX_DOWNSTREAM_PORTS);
		if (ret)
			memset(dig_connector->downstream_ports, 0,
			       DP_MAX_DOWNSTREAM_PORTS);
	}
}

int amdgpu_atombios_dp_get_dpcd(struct amdgpu_connector *amdgpu_connector)
{
	struct amdgpu_connector_atom_dig *dig_connector = amdgpu_connector->con_priv;
	u8 msg[DP_DPCD_SIZE];
	int ret;

	ret = drm_dp_dpcd_read(&amdgpu_connector->ddc_bus->aux, DP_DPCD_REV,
			       msg, DP_DPCD_SIZE);
	if (ret == DP_DPCD_SIZE) {
		memcpy(dig_connector->dpcd, msg, DP_DPCD_SIZE);

		DRM_DEBUG_KMS("DPCD: %*ph\n", (int)sizeof(dig_connector->dpcd),
			      dig_connector->dpcd);

		amdgpu_atombios_dp_probe_oui(amdgpu_connector);
		amdgpu_atombios_dp_ds_ports(amdgpu_connector);
		return 0;
	}

	dig_connector->dpcd[0] = 0;
	return -EINVAL;
}

int amdgpu_atombios_dp_get_panel_mode(struct drm_encoder *encoder,
			       struct drm_connector *connector)
{
	struct amdgpu_connector *amdgpu_connector = to_amdgpu_connector(connector);
	int panel_mode = DP_PANEL_MODE_EXTERNAL_DP_MODE;
	u16 dp_bridge = amdgpu_connector_encoder_get_dp_bridge_encoder_id(connector);
	u8 tmp;

	if (!amdgpu_connector->con_priv)
		return panel_mode;

	if (dp_bridge != ENCODER_OBJECT_ID_NONE) {
		/* DP bridge chips */
		if (drm_dp_dpcd_readb(&amdgpu_connector->ddc_bus->aux,
				      DP_EDP_CONFIGURATION_CAP, &tmp) == 1) {
			if (tmp & 1)
				panel_mode = DP_PANEL_MODE_INTERNAL_DP2_MODE;
			else if ((dp_bridge == ENCODER_OBJECT_ID_NUTMEG) ||
				 (dp_bridge == ENCODER_OBJECT_ID_TRAVIS))
				panel_mode = DP_PANEL_MODE_INTERNAL_DP1_MODE;
			else
				panel_mode = DP_PANEL_MODE_EXTERNAL_DP_MODE;
		}
	} else if (connector->connector_type == DRM_MODE_CONNECTOR_eDP) {
		/* eDP */
		if (drm_dp_dpcd_readb(&amdgpu_connector->ddc_bus->aux,
				      DP_EDP_CONFIGURATION_CAP, &tmp) == 1) {
			if (tmp & 1)
				panel_mode = DP_PANEL_MODE_INTERNAL_DP2_MODE;
		}
	}

	return panel_mode;
}

void amdgpu_atombios_dp_set_link_config(struct drm_connector *connector,
				 const struct drm_display_mode *mode)
{
	struct amdgpu_connector *amdgpu_connector = to_amdgpu_connector(connector);
	struct amdgpu_connector_atom_dig *dig_connector;
	int ret;

	if (!amdgpu_connector->con_priv)
		return;
	dig_connector = amdgpu_connector->con_priv;

	if ((dig_connector->dp_sink_type == CONNECTOR_OBJECT_ID_DISPLAYPORT) ||
	    (dig_connector->dp_sink_type == CONNECTOR_OBJECT_ID_eDP)) {
		ret = amdgpu_atombios_dp_get_dp_link_config(connector, dig_connector->dpcd,
							    mode->clock,
							    &dig_connector->dp_lane_count,
							    &dig_connector->dp_clock);
		if (ret) {
			dig_connector->dp_clock = 0;
			dig_connector->dp_lane_count = 0;
		}
	}
}

int amdgpu_atombios_dp_mode_valid_helper(struct drm_connector *connector,
				  struct drm_display_mode *mode)
{
	struct amdgpu_connector *amdgpu_connector = to_amdgpu_connector(connector);
	struct amdgpu_connector_atom_dig *dig_connector;
	unsigned dp_lanes, dp_clock;
	int ret;

	if (!amdgpu_connector->con_priv)
		return MODE_CLOCK_HIGH;
	dig_connector = amdgpu_connector->con_priv;

	ret = amdgpu_atombios_dp_get_dp_link_config(connector, dig_connector->dpcd,
						    mode->clock, &dp_lanes, &dp_clock);
	if (ret)
		return MODE_CLOCK_HIGH;

	if ((dp_clock == 540000) &&
	    (!amdgpu_connector_is_dp12_capable(connector)))
		return MODE_CLOCK_HIGH;

	return MODE_OK;
}

bool amdgpu_atombios_dp_needs_link_train(struct amdgpu_connector *amdgpu_connector)
{
	u8 link_status[DP_LINK_STATUS_SIZE];
	struct amdgpu_connector_atom_dig *dig = amdgpu_connector->con_priv;

	if (drm_dp_dpcd_read_link_status(&amdgpu_connector->ddc_bus->aux, link_status)
	    <= 0)
		return false;
	if (drm_dp_channel_eq_ok(link_status, dig->dp_lane_count))
		return false;
	return true;
}

void amdgpu_atombios_dp_set_rx_power_state(struct drm_connector *connector,
				    u8 power_state)
{
	struct amdgpu_connector *amdgpu_connector = to_amdgpu_connector(connector);
	struct amdgpu_connector_atom_dig *dig_connector;

	if (!amdgpu_connector->con_priv)
		return;

	dig_connector = amdgpu_connector->con_priv;

	/* power up/down the sink */
	if (dig_connector->dpcd[0] >= 0x11) {
		drm_dp_dpcd_writeb(&amdgpu_connector->ddc_bus->aux,
				   DP_SET_POWER, power_state);
		usleep_range(1000, 2000);
	}
}

struct amdgpu_atombios_dp_link_train_info {
	struct amdgpu_device *adev;
	struct drm_encoder *encoder;
	struct drm_connector *connector;
	int dp_clock;
	int dp_lane_count;
	bool tp3_supported;
	u8 dpcd[DP_RECEIVER_CAP_SIZE];
	u8 train_set[4];
	u8 link_status[DP_LINK_STATUS_SIZE];
	u8 tries;
	struct drm_dp_aux *aux;
};

static void
amdgpu_atombios_dp_update_vs_emph(struct amdgpu_atombios_dp_link_train_info *dp_info)
{
	/* set the initial vs/emph on the source */
	amdgpu_atombios_encoder_setup_dig_transmitter(dp_info->encoder,
					       ATOM_TRANSMITTER_ACTION_SETUP_VSEMPH,
					       0, dp_info->train_set[0]); /* sets all lanes at once */

	/* set the vs/emph on the sink */
	drm_dp_dpcd_write(dp_info->aux, DP_TRAINING_LANE0_SET,
			  dp_info->train_set, dp_info->dp_lane_count);
}

static void
amdgpu_atombios_dp_set_tp(struct amdgpu_atombios_dp_link_train_info *dp_info, int tp)
{
	int rtp = 0;

	/* set training pattern on the source */
	switch (tp) {
	case DP_TRAINING_PATTERN_1:
		rtp = ATOM_ENCODER_CMD_DP_LINK_TRAINING_PATTERN1;
		break;
	case DP_TRAINING_PATTERN_2:
		rtp = ATOM_ENCODER_CMD_DP_LINK_TRAINING_PATTERN2;
		break;
	case DP_TRAINING_PATTERN_3:
		rtp = ATOM_ENCODER_CMD_DP_LINK_TRAINING_PATTERN3;
			break;
	}
	amdgpu_atombios_encoder_setup_dig_encoder(dp_info->encoder, rtp, 0);

	/* enable training pattern on the sink */
	drm_dp_dpcd_writeb(dp_info->aux, DP_TRAINING_PATTERN_SET, tp);
}

static int
amdgpu_atombios_dp_link_train_init(struct amdgpu_atombios_dp_link_train_info *dp_info)
{
	struct amdgpu_encoder *amdgpu_encoder = to_amdgpu_encoder(dp_info->encoder);
	struct amdgpu_encoder_atom_dig *dig = amdgpu_encoder->enc_priv;
	u8 tmp;

	/* power up the sink */
	amdgpu_atombios_dp_set_rx_power_state(dp_info->connector, DP_SET_POWER_D0);

	/* possibly enable downspread on the sink */
	if (dp_info->dpcd[3] & 0x1)
		drm_dp_dpcd_writeb(dp_info->aux,
				   DP_DOWNSPREAD_CTRL, DP_SPREAD_AMP_0_5);
	else
		drm_dp_dpcd_writeb(dp_info->aux,
				   DP_DOWNSPREAD_CTRL, 0);

	if (dig->panel_mode == DP_PANEL_MODE_INTERNAL_DP2_MODE)
		drm_dp_dpcd_writeb(dp_info->aux, DP_EDP_CONFIGURATION_SET, 1);

	/* set the lane count on the sink */
	tmp = dp_info->dp_lane_count;
	if (drm_dp_enhanced_frame_cap(dp_info->dpcd))
		tmp |= DP_LANE_COUNT_ENHANCED_FRAME_EN;
	drm_dp_dpcd_writeb(dp_info->aux, DP_LANE_COUNT_SET, tmp);

	/* set the link rate on the sink */
	tmp = drm_dp_link_rate_to_bw_code(dp_info->dp_clock);
	drm_dp_dpcd_writeb(dp_info->aux, DP_LINK_BW_SET, tmp);

	/* start training on the source */
	amdgpu_atombios_encoder_setup_dig_encoder(dp_info->encoder,
					   ATOM_ENCODER_CMD_DP_LINK_TRAINING_START, 0);

	/* disable the training pattern on the sink */
	drm_dp_dpcd_writeb(dp_info->aux,
			   DP_TRAINING_PATTERN_SET,
			   DP_TRAINING_PATTERN_DISABLE);

	return 0;
}

static int
amdgpu_atombios_dp_link_train_finish(struct amdgpu_atombios_dp_link_train_info *dp_info)
{
	udelay(400);

	/* disable the training pattern on the sink */
	drm_dp_dpcd_writeb(dp_info->aux,
			   DP_TRAINING_PATTERN_SET,
			   DP_TRAINING_PATTERN_DISABLE);

	/* disable the training pattern on the source */
	amdgpu_atombios_encoder_setup_dig_encoder(dp_info->encoder,
					   ATOM_ENCODER_CMD_DP_LINK_TRAINING_COMPLETE, 0);

	return 0;
}

static int
amdgpu_atombios_dp_link_train_cr(struct amdgpu_atombios_dp_link_train_info *dp_info)
{
	bool clock_recovery;
	u8 voltage;
	int i;

	amdgpu_atombios_dp_set_tp(dp_info, DP_TRAINING_PATTERN_1);
	memset(dp_info->train_set, 0, 4);
	amdgpu_atombios_dp_update_vs_emph(dp_info);

	udelay(400);

	/* clock recovery loop */
	clock_recovery = false;
	dp_info->tries = 0;
	voltage = 0xff;
	while (1) {
		drm_dp_link_train_clock_recovery_delay(dp_info->dpcd);

		if (drm_dp_dpcd_read_link_status(dp_info->aux,
						 dp_info->link_status) <= 0) {
			DRM_ERROR("displayport link status failed\n");
			break;
		}

		if (drm_dp_clock_recovery_ok(dp_info->link_status, dp_info->dp_lane_count)) {
			clock_recovery = true;
			break;
		}

		for (i = 0; i < dp_info->dp_lane_count; i++) {
			if ((dp_info->train_set[i] & DP_TRAIN_MAX_SWING_REACHED) == 0)
				break;
		}
		if (i == dp_info->dp_lane_count) {
			DRM_ERROR("clock recovery reached max voltage\n");
			break;
		}

		if ((dp_info->train_set[0] & DP_TRAIN_VOLTAGE_SWING_MASK) == voltage) {
			++dp_info->tries;
			if (dp_info->tries == 5) {
				DRM_ERROR("clock recovery tried 5 times\n");
				break;
			}
		} else
			dp_info->tries = 0;

		voltage = dp_info->train_set[0] & DP_TRAIN_VOLTAGE_SWING_MASK;

		/* Compute new train_set as requested by sink */
		amdgpu_atombios_dp_get_adjust_train(dp_info->link_status, dp_info->dp_lane_count,
					     dp_info->train_set);

		amdgpu_atombios_dp_update_vs_emph(dp_info);
	}
	if (!clock_recovery) {
		DRM_ERROR("clock recovery failed\n");
		return -1;
	} else {
		DRM_DEBUG_KMS("clock recovery at voltage %d pre-emphasis %d\n",
			  dp_info->train_set[0] & DP_TRAIN_VOLTAGE_SWING_MASK,
			  (dp_info->train_set[0] & DP_TRAIN_PRE_EMPHASIS_MASK) >>
			  DP_TRAIN_PRE_EMPHASIS_SHIFT);
		return 0;
	}
}

static int
amdgpu_atombios_dp_link_train_ce(struct amdgpu_atombios_dp_link_train_info *dp_info)
{
	bool channel_eq;

	if (dp_info->tp3_supported)
		amdgpu_atombios_dp_set_tp(dp_info, DP_TRAINING_PATTERN_3);
	else
		amdgpu_atombios_dp_set_tp(dp_info, DP_TRAINING_PATTERN_2);

	/* channel equalization loop */
	dp_info->tries = 0;
	channel_eq = false;
	while (1) {
		drm_dp_link_train_channel_eq_delay(dp_info->dpcd);

		if (drm_dp_dpcd_read_link_status(dp_info->aux,
						 dp_info->link_status) <= 0) {
			DRM_ERROR("displayport link status failed\n");
			break;
		}

		if (drm_dp_channel_eq_ok(dp_info->link_status, dp_info->dp_lane_count)) {
			channel_eq = true;
			break;
		}

		/* Try 5 times */
		if (dp_info->tries > 5) {
			DRM_ERROR("channel eq failed: 5 tries\n");
			break;
		}

		/* Compute new train_set as requested by sink */
		amdgpu_atombios_dp_get_adjust_train(dp_info->link_status, dp_info->dp_lane_count,
					     dp_info->train_set);

		amdgpu_atombios_dp_update_vs_emph(dp_info);
		dp_info->tries++;
	}

	if (!channel_eq) {
		DRM_ERROR("channel eq failed\n");
		return -1;
	} else {
		DRM_DEBUG_KMS("channel eq at voltage %d pre-emphasis %d\n",
			  dp_info->train_set[0] & DP_TRAIN_VOLTAGE_SWING_MASK,
			  (dp_info->train_set[0] & DP_TRAIN_PRE_EMPHASIS_MASK)
			  >> DP_TRAIN_PRE_EMPHASIS_SHIFT);
		return 0;
	}
}

void amdgpu_atombios_dp_link_train(struct drm_encoder *encoder,
			    struct drm_connector *connector)
{
	struct drm_device *dev = encoder->dev;
	struct amdgpu_device *adev = drm_to_adev(dev);
	struct amdgpu_encoder *amdgpu_encoder = to_amdgpu_encoder(encoder);
	struct amdgpu_connector *amdgpu_connector;
	struct amdgpu_connector_atom_dig *dig_connector;
	struct amdgpu_atombios_dp_link_train_info dp_info;
	u8 tmp;

	if (!amdgpu_encoder->enc_priv)
		return;

	amdgpu_connector = to_amdgpu_connector(connector);
	if (!amdgpu_connector->con_priv)
		return;
	dig_connector = amdgpu_connector->con_priv;

	if ((dig_connector->dp_sink_type != CONNECTOR_OBJECT_ID_DISPLAYPORT) &&
	    (dig_connector->dp_sink_type != CONNECTOR_OBJECT_ID_eDP))
		return;

	if (drm_dp_dpcd_readb(&amdgpu_connector->ddc_bus->aux, DP_MAX_LANE_COUNT, &tmp)
	    == 1) {
		if (tmp & DP_TPS3_SUPPORTED)
			dp_info.tp3_supported = true;
		else
			dp_info.tp3_supported = false;
	} else {
		dp_info.tp3_supported = false;
	}

	memcpy(dp_info.dpcd, dig_connector->dpcd, DP_RECEIVER_CAP_SIZE);
	dp_info.adev = adev;
	dp_info.encoder = encoder;
	dp_info.connector = connector;
	dp_info.dp_lane_count = dig_connector->dp_lane_count;
	dp_info.dp_clock = dig_connector->dp_clock;
	dp_info.aux = &amdgpu_connector->ddc_bus->aux;

	if (amdgpu_atombios_dp_link_train_init(&dp_info))
		goto done;
	if (amdgpu_atombios_dp_link_train_cr(&dp_info))
		goto done;
	if (amdgpu_atombios_dp_link_train_ce(&dp_info))
		goto done;
done:
	if (amdgpu_atombios_dp_link_train_finish(&dp_info))
		return;
}