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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
This commit is contained in:
Koba Ko 2020-09-22 14:53:13 +08:00 committed by Lyude Paul
parent 9572e6693c
commit ad44c03208
1 changed files with 4 additions and 3 deletions
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7
drivers/gpu/drm/drm_dp_mst_topology.c
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@ -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;
}