drm/amd/display: Release MST resources on switch from MST to SST

[ 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@amd.com>
Reviewed-by: Wenjing Liu <Wenjing.Liu@amd.com>
Acked-by: Stylon Wang <stylon.wang@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

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 32b73ea..a7f8caf 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
@@ -1704,6 +1704,8 @@ 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) {