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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: Wenjing Liu <Wenjing.Liu@amd.com>
Acked-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Ilya Bakoulin <Ilya.Bakoulin@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Ilya Bakoulin 2022-11-02 15:56:16 -04:00 committed by Alex Deucher
parent 158858bf1a
commit 180f33d27a
1 changed files with 11 additions and 9 deletions
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8
drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
View File

@ -1912,7 +1912,7 @@ enum dc_status dpcd_configure_lttpr_mode(struct dc_link *link, struct link_train
return status; 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 sink_status = 0;
uint8_t i; uint8_t i;
@ -1920,6 +1920,7 @@ static void dpcd_exit_training_mode(struct dc_link *link)
/* clear training pattern set */ /* clear training pattern set */
dpcd_set_training_pattern(link, DP_TRAINING_PATTERN_VIDEOIDLE); dpcd_set_training_pattern(link, DP_TRAINING_PATTERN_VIDEOIDLE);
if (encoding == DP_128b_132b_ENCODING) {
/* poll for intra-hop disable */ /* poll for intra-hop disable */
for (i = 0; i < 10; i++) { for (i = 0; i < 10; i++) {
if ((core_link_read_dpcd(link, DP_SINK_STATUS, &sink_status, 1) == DC_OK) && if ((core_link_read_dpcd(link, DP_SINK_STATUS, &sink_status, 1) == DC_OK) &&
@ -1927,6 +1928,7 @@ static void dpcd_exit_training_mode(struct dc_link *link)
break; break;
udelay(1000); udelay(1000);
} }
}
} }
enum dc_status dpcd_configure_channel_coding(struct dc_link *link, enum dc_status dpcd_configure_channel_coding(struct dc_link *link,
@ -2649,7 +2651,7 @@ enum link_training_result dc_link_dp_perform_link_training(
&lt_settings); &lt_settings);
/* reset previous training states */ /* reset previous training states */
dpcd_exit_training_mode(link); dpcd_exit_training_mode(link, encoding);
/* configure link prior to entering training mode */ /* configure link prior to entering training mode */
dpcd_configure_lttpr_mode(link, &lt_settings); dpcd_configure_lttpr_mode(link, &lt_settings);
@ -2670,7 +2672,7 @@ enum link_training_result dc_link_dp_perform_link_training(
ASSERT(0); ASSERT(0);
/* exit training mode */ /* exit training mode */
dpcd_exit_training_mode(link); dpcd_exit_training_mode(link, encoding);
/* switch to video idle */ /* switch to video idle */
if ((status == LINK_TRAINING_SUCCESS) || !skip_video_pattern) if ((status == LINK_TRAINING_SUCCESS) || !skip_video_pattern)