From 507aa8d3483993369e4d7b20898cedea60b1c6fe Mon Sep 17 00:00:00 2001
From: George Shen <George.Shen@amd.com>
Date: Fri, 19 Nov 2021 11:09:37 -0500
Subject: drm/amd/display: Add 16ms AUX RD interval W/A for specific LTTPR
Git-commit: ee347d5b40a14dd9a80dfb2bf4d2c5b3b4367135
Patch-mainline: v5.17-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225
[Why]
Certain display configurations require an extra delay before
reading lane status with certain LTTPR.
[How]
Add temporary workaround to force AUX RD interval to
16ms for CR and EQ. Needs to be refactored later.
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: George Shen <George.Shen@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
index 81b0a01615c3..62510b643882 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
@@ -1384,6 +1384,12 @@ static enum link_training_result perform_channel_equalization_sequence(
dp_translate_training_aux_read_interval(
link->dpcd_caps.lttpr_caps.aux_rd_interval[offset - 1]);
+ if (link->dc->debug.apply_vendor_specific_lttpr_wa &&
+ (link->chip_caps & EXT_DISPLAY_PATH_CAPS__DP_FIXED_VS_EN) &&
+ link->lttpr_mode == LTTPR_MODE_TRANSPARENT) {
+ wait_time_microsec = 16000;
+ }
+
dp_wait_for_training_aux_rd_interval(
link,
wait_time_microsec);
@@ -1487,6 +1493,12 @@ static enum link_training_result perform_clock_recovery_sequence(
if (link->lttpr_mode == LTTPR_MODE_NON_TRANSPARENT)
wait_time_microsec = TRAINING_AUX_RD_INTERVAL;
+ if (link->dc->debug.apply_vendor_specific_lttpr_wa &&
+ (link->chip_caps & EXT_DISPLAY_PATH_CAPS__DP_FIXED_VS_EN) &&
+ link->lttpr_mode == LTTPR_MODE_TRANSPARENT) {
+ wait_time_microsec = 16000;
+ }
+
dp_wait_for_training_aux_rd_interval(
link,
wait_time_microsec);
--
2.38.1