linux-kernel - [PATCH AUTOSEL 6.12 364/486] drm/amd/display: Don't try AUX transactions on disconnected link

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Message-Id: <20250505223922.2682012-364-sashal@kernel.org>
Date: Mon,  5 May 2025 18:37:20 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Ilya Bakoulin <Ilya.Bakoulin@....com>,
	Wenjing Liu <wenjing.liu@....com>,
	Aurabindo Pillai <aurabindo.pillai@....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,
	chiahsuan.chung@....com,
	zaeem.mohamed@....com,
	PeiChen.Huang@....com,
	michael.strauss@....com,
	amd-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 6.12 364/486] drm/amd/display: Don't try AUX transactions on disconnected link

From: Ilya Bakoulin <Ilya.Bakoulin@....com>

[ Upstream commit e8bffa52e0253cfd689813a620e64521256bc712 ]

[Why]
Setting link DPMS off in response to HPD disconnect creates AUX
transactions on a link that is supposed to be disconnected. This can
cause issues in some cases when the sink re-asserts HPD and expects
source to re-enable the link.

[How]
Avoid AUX transactions on disconnected link.

Reviewed-by: Wenjing Liu <wenjing.liu@....com>
Signed-off-by: Ilya Bakoulin <Ilya.Bakoulin@....com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@....com>
Tested-by: Daniel Wheeler <daniel.wheeler@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 .../gpu/drm/amd/display/dc/link/protocols/link_dp_phy.c   | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_phy.c b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_phy.c
index bafa52a0165a0..17c57cf98ec5c 100644
--- a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_phy.c
+++ b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_phy.c
@@ -75,7 +75,8 @@ void dp_disable_link_phy(struct dc_link *link,
 	struct dc  *dc = link->ctx->dc;
 
 	if (!link->wa_flags.dp_keep_receiver_powered &&
-		!link->skip_implict_edp_power_control)
+			!link->skip_implict_edp_power_control &&
+			link->type != dc_connection_none)
 		dpcd_write_rx_power_ctrl(link, false);
 
 	dc->hwss.disable_link_output(link, link_res, signal);
@@ -163,8 +164,9 @@ enum dc_status dp_set_fec_ready(struct dc_link *link, const struct link_resource
 	} else {
 		if (link->fec_state == dc_link_fec_ready) {
 			fec_config = 0;
-			core_link_write_dpcd(link, DP_FEC_CONFIGURATION,
-				&fec_config, sizeof(fec_config));
+			if (link->type != dc_connection_none)
+				core_link_write_dpcd(link, DP_FEC_CONFIGURATION,
+					&fec_config, sizeof(fec_config));
 
 			link_enc->funcs->fec_set_ready(link_enc, false);
 			link->fec_state = dc_link_fec_not_ready;
-- 
2.39.5