drm/amd/display: Defer handling mst up request in resume

[Why]
Like commit ec5fa9fcdeca ("drm/amd/display: Adjust the MST resume flow"), we
want to avoid handling mst topology changes before restoring the old state.
If we enable DP_UP_REQ_EN before calling drm_atomic_helper_resume(), have
changce to handle CSN event first and fire hotplug event before restoring the
cached state.

[How]
Disable mst branch sending up request event before we restoring the cached state.
DP_UP_REQ_EN will be set later when we call drm_dp_mst_topology_mgr_resume().

Cc: Mario Limonciello <[email protected]>
Cc: Alex Deucher <[email protected]>
Cc: [email protected]
Reviewed-by: Hersen Wu <[email protected]>
Signed-off-by: Wayne Lin <[email protected]>
Tested-by: Daniel Wheeler <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>

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 c863f400024b4196367a30e06d22dc87f3a00b65..ecf5752ef35f97dd7f5713b097bdb9c73a995e02 100644 (file)
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -2429,7 +2429,6 @@ static void resume_mst_branch_status(struct drm_dp_mst_topology_mgr *mgr)
 
        ret = drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL,
                                 DP_MST_EN |
-                                DP_UP_REQ_EN |
                                 DP_UPSTREAM_IS_SRC);
        if (ret < 0) {
                drm_dbg_kms(mgr->dev, "mst write failed - undocked during suspend?\n");