drm/dp_mst: Retrieve extended DPCD caps for topology manager

As per DP-1.3, First check DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT.
If DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT is 1,read the DP_DP13_DPCD_REV to
get the faster capability.
If DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT is 0,read DP_DPCD_REV.

Signed-off-by: Koba Ko <koba.ko@canonical.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
[added aux name to drm_dbg_kms() call]
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200922065313.4794-1-koba.ko@canonical.com

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index b9c5a98c5c9ce38e43d098067df50c379e705ab2..b4a4bb340910fdf66676fb4e9f084d6dd1cf1d92 100644 (file)
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -3536,9 +3536,10 @@ int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool ms
                WARN_ON(mgr->mst_primary);
 
                /* get dpcd info */
-               ret = drm_dp_dpcd_read(mgr->aux, DP_DPCD_REV, mgr->dpcd, DP_RECEIVER_CAP_SIZE);
-               if (ret != DP_RECEIVER_CAP_SIZE) {
-                       DRM_DEBUG_KMS("failed to read DPCD\n");
+               ret = drm_dp_read_dpcd_caps(mgr->aux, mgr->dpcd);
+               if (ret < 0) {
+                       drm_dbg_kms(mgr->dev, "%s: failed to read DPCD, ret %d\n",
+                                   mgr->aux->name, ret);
                        goto out_unlock;
                }