Commit 180f33d2 authored by Ilya Bakoulin's avatar Ilya Bakoulin Committed by Alex Deucher
Browse files

drm/amd/display: Adjust DP 8b10b LT exit behavior 



[Why]
Polling SINK_STATUS DPCD can cause some non-DP2.0 LTTPR hubs to hang and
no longer respond to AUX.

[How]
As a workaround for the problem hubs, and also to more closely match
DP spec 8b10b behavior, don't poll for intra-hop AUX reply indication
on 8b10b-encoded links.

Reviewed-by: default avatarWenjing Liu <Wenjing.Liu@amd.com>
Acked-by: default avatarTom Chung <chiahsuan.chung@amd.com>
Signed-off-by: default avatarIlya Bakoulin <Ilya.Bakoulin@amd.com>
Tested-by: default avatarDaniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent 158858bf

drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c

+11 −9
Original line number Diff line number Diff line
@@ -1912,7 +1912,7 @@ enum dc_status dpcd_configure_lttpr_mode(struct dc_link *link, struct link_train 
	return status;

}



static void dpcd_exit_training_mode(struct dc_link *link)

static void dpcd_exit_training_mode(struct dc_link *link, enum dp_link_encoding encoding)

{

	uint8_t sink_status = 0;

	uint8_t i;
@@ -1920,6 +1920,7 @@ static void dpcd_exit_training_mode(struct dc_link *link) 
	/* clear training pattern set */

	dpcd_set_training_pattern(link, DP_TRAINING_PATTERN_VIDEOIDLE);



	if (encoding == DP_128b_132b_ENCODING) {

		/* poll for intra-hop disable */

		for (i = 0; i < 10; i++) {

			if ((core_link_read_dpcd(link, DP_SINK_STATUS, &sink_status, 1) == DC_OK) &&
@@ -1928,6 +1929,7 @@ static void dpcd_exit_training_mode(struct dc_link *link) 
			udelay(1000);

		}

	}

}



enum dc_status dpcd_configure_channel_coding(struct dc_link *link,

		struct link_training_settings *lt_settings)
@@ -2649,7 +2651,7 @@ enum link_training_result dc_link_dp_perform_link_training( 
			&lt_settings);



	/* reset previous training states */

	dpcd_exit_training_mode(link);

	dpcd_exit_training_mode(link, encoding);



	/* configure link prior to entering training mode */

	dpcd_configure_lttpr_mode(link, &lt_settings);
@@ -2670,7 +2672,7 @@ enum link_training_result dc_link_dp_perform_link_training( 
		ASSERT(0);



	/* exit training mode */

	dpcd_exit_training_mode(link);

	dpcd_exit_training_mode(link, encoding);



	/* switch to video idle */

	if ((status == LINK_TRAINING_SUCCESS) || !skip_video_pattern)