From 3001d2073d6542a9e51fa5bca3a39a078094d3c6 Mon Sep 17 00:00:00 2001 From: Fangzhi Zuo Date: Thu, 27 Aug 2026 13:12:46 -0400 Subject: [PATCH] drm/amd/display: Exit IPS before connector detection on resume [Why & How] On resume, dm_resume() walks the connector list and, for each connector, calls dc_link_detect_connection_type() at the top of the loop iteration before the per-connector dc_exit_ips_for_hw_access() that sits in the detection branch. There is no dc_exit_ips_for_hw_access() before the loop, so the very first HW access relies on an earlier connector having already taken the display out of IPS. Commit d1d51519bc3b ("drm/amd/display: Skip eDP detection when no sink") skips the eDP connector when no panel is present. On a DCN3.5 APU whose eDP link has no sink, the eDP iteration - which used to bring the HW out of IPS first - is now skipped, so a downstream DP connector becomes the first one processed. Its initial DDC/AUX access then runs while the HW is still idle, the AUX transfers time out (-ETIMEDOUT), and the EDID read fails: [drm:dm_helpers_read_local_edid [amdgpu]] *ERROR* EDID err: 2, on connector: DP-1 amdgpu: [drm] *ERROR* No EDID read. Take the display out of IPS once before the detection loop so the first connector processed no longer touches the AUX/DDC engine while the HW is still in idle power state. This keeps the eDP-skip boot/resume optimization while fixing the DP EDID read failure. Fixes: d1d51519bc3b ("drm/amd/display: Skip eDP detection when no sink") Reviewed-by: Roman Li Signed-off-by: Fangzhi Zuo Signed-off-by: Ray Wu Tested-by: Dan Wheeler Signed-off-by: Alex Deucher (cherry picked from commit 86420fe3093161971b4064e05be11ffff1df76aa) Cc: stable@vger.kernel.org --- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 4 ++++ 1 file changed, 4 insertions(+) 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 a95243656f54..08b8605029ab 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c @@ -1972,6 +1972,10 @@ static int dm_resume(struct amdgpu_ip_block *ip_block) /* On resume we need to rewrite the MSTM control bits to enable MST*/ s3_handle_mst(ddev, false); + /* Exit IPS before the detection loop's first AUX/DDC access. */ + scoped_guard(mutex, &dm->dc_lock) + dc_exit_ips_for_hw_access(dm->dc); + /* Do detection*/ drm_connector_list_iter_begin(ddev, &iter); drm_for_each_connector_iter(connector, &iter) {