drm/amd/display: Fix topology change issue in MST rehook

When topology changed and rehook up MST display to the same DP
connector, need to take care of drm_dp_mst_port object.

Due to the topology is changed, drm_dp_mst_port and corresponding
i2c_algorithm object could be NULL in such situation.

Signed-off-by: Jerry (Fangzhi) Zuo <Jerry.Zuo@amd.com>
Reviewed-by: Roman Li <Roman.Li@amd.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
index f3d87f4..93421da 100644 (file)
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
@@ -189,6 +189,12 @@ void dm_dp_mst_dc_sink_create(struct drm_connector *connector)
                        .link = aconnector->dc_link,
                        .sink_signal = SIGNAL_TYPE_DISPLAY_PORT_MST };
 
+       /*
+        * TODO: Need to further figure out why ddc.algo is NULL while MST port exists
+        */
+       if (!aconnector->port || !aconnector->port->aux.ddc.algo)
+               return;
+
        edid = drm_dp_mst_get_edid(connector, &aconnector->mst_port->mst_mgr, aconnector->port);
 
        if (!edid) {