[PATCH AUTOSEL 5.13 091/189] drm/amd/display: Release MST resources on switch from MST to SST

[Sasha Levin]

From: Vladimir Stempen <vladimir.stem...@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.stem...@amd.com>
Reviewed-by: Wenjing Liu <wenjing....@amd.com>
Acked-by: Stylon Wang <stylon.w...@amd.com>
Tested-by: Daniel Wheeler <daniel.whee...@amd.com>
Signed-off-by: Alex Deucher <alexander.deuc...@amd.com>
Signed-off-by: Sasha Levin <sas...@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 3ff3d9e90983..f26ed50a9660 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
@@ -1784,6 +1784,8 @@ 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