From aa4be25f41f343b23d3ef6cb344740e03a72d7cf Mon Sep 17 00:00:00 2001 From: Wayne Lin Date: Wed, 5 Nov 2025 10:36:31 +0800 Subject: drm/amd/display: Enable mst when it's detected but yet to be initialized commit 3c6a743c6961cc2cab453b343bb157d6bbbf8120 upstream. [Why] drm_dp_mst_topology_queue_probe() is used under the assumption that mst is already initialized. If we connect system with SST first then switch to the mst branch during suspend, we will fail probing topology by calling the wrong API since the mst manager is yet to be initialized. [How] At dm_resume(), once it's detected as mst branc connected, check if the mst is initialized already. If not, call dm_helpers_dp_mst_start_top_mgr() instead to initialize mst V2: Adjust the commit msg a bit Fixes: bc068194f548 ("drm/amd/display: Don't write DP_MSTM_CTRL after LT") Cc: Fangzhi Zuo Cc: Mario Limonciello Cc: Alex Deucher Reviewed-by: Tom Chung Signed-off-by: Wayne Lin Signed-off-by: Alex Deucher (cherry picked from commit 62320fb8d91a0bddc44a228203cfa9bfbb5395bd) Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c index 271710104f0e..cd8c6887a3b5 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c @@ -3424,6 +3424,7 @@ static int dm_resume(void *handle) /* Do mst topology probing after resuming cached state*/ drm_connector_list_iter_begin(ddev, &iter); drm_for_each_connector_iter(connector, &iter) { + bool init = false; if (connector->connector_type == DRM_MODE_CONNECTOR_WRITEBACK) continue; @@ -3433,7 +3434,14 @@ static int dm_resume(void *handle) aconnector->mst_root) continue; - drm_dp_mst_topology_queue_probe(&aconnector->mst_mgr); + scoped_guard(mutex, &aconnector->mst_mgr.lock) { + init = !aconnector->mst_mgr.mst_primary; + } + if (init) + dm_helpers_dp_mst_start_top_mgr(aconnector->dc_link->ctx, + aconnector->dc_link, false); + else + drm_dp_mst_topology_queue_probe(&aconnector->mst_mgr); } drm_connector_list_iter_end(&iter); -- cgit v1.2.3