linux-kernel - [PATCH AUTOSEL 6.6 225/294] drm/amd/display: Update CR AUX RD interval interpretation

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Message-Id: <20250505225634.2688578-225-sashal@kernel.org>
Date: Mon,  5 May 2025 18:55:25 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: George Shen <george.shen@....com>,
	Michael Strauss <michael.strauss@....com>,
	Wenjing Liu <wenjing.liu@....com>,
	Zaeem Mohamed <zaeem.mohamed@....com>,
	Daniel Wheeler <daniel.wheeler@....com>,
	Alex Deucher <alexander.deucher@....com>,
	Sasha Levin <sashal@...nel.org>,
	harry.wentland@....com,
	sunpeng.li@....com,
	christian.koenig@....com,
	airlied@...il.com,
	simona@...ll.ch,
	PeiChen.Huang@....com,
	amd-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 6.6 225/294] drm/amd/display: Update CR AUX RD interval interpretation

From: George Shen <george.shen@....com>

[ Upstream commit 6a7fde433231c18164c117592d3e18ced648ad58 ]

[Why]
DP spec updated to have the CR AUX RD interval match the EQ AUX RD
interval interpretation of DPCD 0000Eh/0220Eh for 8b/10b non-LTTPR mode
and LTTPR transparent mode cases.

[How]
Update interpretation of DPCD 0000Eh/0220Eh for CR AUX RD interval
during 8b/10b link training.

Reviewed-by: Michael Strauss <michael.strauss@....com>
Reviewed-by: Wenjing Liu <wenjing.liu@....com>
Signed-off-by: George Shen <george.shen@....com>
Signed-off-by: Zaeem Mohamed <zaeem.mohamed@....com>
Tested-by: Daniel Wheeler <daniel.wheeler@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 .../display/dc/link/protocols/link_dp_training_8b_10b.c    | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_training_8b_10b.c b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_training_8b_10b.c
index 2b4c15b0b4070..52261e7c11c0b 100644
--- a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_training_8b_10b.c
+++ b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_training_8b_10b.c
@@ -36,7 +36,8 @@
 	link->ctx->logger
 
 static int32_t get_cr_training_aux_rd_interval(struct dc_link *link,
-		const struct dc_link_settings *link_settings)
+		const struct dc_link_settings *link_settings,
+		enum lttpr_mode lttpr_mode)
 {
 	union training_aux_rd_interval training_rd_interval;
 	uint32_t wait_in_micro_secs = 100;
@@ -49,6 +50,8 @@ static int32_t get_cr_training_aux_rd_interval(struct dc_link *link,
 				DP_TRAINING_AUX_RD_INTERVAL,
 				(uint8_t *)&training_rd_interval,
 				sizeof(training_rd_interval));
+		if (lttpr_mode != LTTPR_MODE_NON_TRANSPARENT)
+			wait_in_micro_secs = 400;
 		if (training_rd_interval.bits.TRAINIG_AUX_RD_INTERVAL)
 			wait_in_micro_secs = training_rd_interval.bits.TRAINIG_AUX_RD_INTERVAL * 4000;
 	}
@@ -110,7 +113,6 @@ void decide_8b_10b_training_settings(
 	 */
 	lt_settings->link_settings.link_spread = link->dp_ss_off ?
 			LINK_SPREAD_DISABLED : LINK_SPREAD_05_DOWNSPREAD_30KHZ;
-	lt_settings->cr_pattern_time = get_cr_training_aux_rd_interval(link, link_setting);
 	lt_settings->eq_pattern_time = get_eq_training_aux_rd_interval(link, link_setting);
 	lt_settings->pattern_for_cr = decide_cr_training_pattern(link_setting);
 	lt_settings->pattern_for_eq = decide_eq_training_pattern(link, link_setting);
@@ -119,6 +121,7 @@ void decide_8b_10b_training_settings(
 	lt_settings->disallow_per_lane_settings = true;
 	lt_settings->always_match_dpcd_with_hw_lane_settings = true;
 	lt_settings->lttpr_mode = dp_decide_8b_10b_lttpr_mode(link);
+	lt_settings->cr_pattern_time = get_cr_training_aux_rd_interval(link, link_setting, lt_settings->lttpr_mode);
 	dp_hw_to_dpcd_lane_settings(lt_settings, lt_settings->hw_lane_settings, lt_settings->dpcd_lane_settings);
 }
 
-- 
2.39.5