[PATCH AUTOSEL 5.12 077/160] drm/amd/display: Release MST resources on switch from MST to SST

[Sasha Levin]

From: Vladimir Stempen <vladimir.stempen at amd.com>

[ Upstream commit 3f8518b60c10aa96f3efa38a967a0b4eb9211ac0 ]

[why]
When OS overrides training link training parameters
for MST device to SST mode, MST resources are not
released and leak of the resource may result crash and
incorrect MST discovery during following hot plugs.

[how]
Retaining sink object to be reused by SST link and
releasing MST  resources.

Signed-off-by: Vladimir Stempen <vladimir.stempen at amd.com>
Reviewed-by: Wenjing Liu <Wenjing.Liu at amd.com>
Acked-by: Stylon Wang <stylon.wang at amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler at amd.com>
Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
Signed-off-by: Sasha Levin <sashal at kernel.org>
---
 drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c | 2 ++
 1 file changed, 2 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 c1391bfb7a9b..208454df17d7 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
@@ -1726,6 +1726,8 @@ static void set_dp_mst_mode(struct dc_link *link, bool mst_enable)
 		link->type = dc_connection_single;
 		link->local_sink = link->remote_sinks[0];
 		link->local_sink->sink_signal = SIGNAL_TYPE_DISPLAY_PORT;
+		dc_sink_retain(link->local_sink);
+		dm_helpers_dp_mst_stop_top_mgr(link->ctx, link);
 	} else if (mst_enable == true &&
 			link->type == dc_connection_single &&
 			link->remote_sinks[0] != NULL) {
-- 
2.30.2