From 3c6a743c6961cc2cab453b343bb157d6bbbf8120 Mon Sep 17 00:00:00 2001 From: Wayne Lin Date: Wed, 5 Nov 2025 10:36:31 +0800 Subject: [PATCH] drm/amd/display: Enable mst when it's detected but yet to be initialized [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 --- 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 2fe6520207d6..91c0188a29b2 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c @@ -3563,6 +3563,7 @@ static int dm_resume(struct amdgpu_ip_block *ip_block) /* 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; @@ -3572,7 +3573,14 @@ static int dm_resume(struct amdgpu_ip_block *ip_block) 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); -- 2.47.3