drm/dp/mst: Read the extended DPCD capabilities during system resume

[ Upstream commit 7a710a8bc909313951eb9252d8419924c771d7c2 ]

The WD22TB4 Thunderbolt dock at least will revert its DP_MAX_LINK_RATE
from HBR3 to HBR2 after system suspend/resume if the DP_DP13_DPCD_REV
registers are not read subsequently also as required.

Fix this by reading DP_DP13_DPCD_REV registers as well, matching what is
done during connector detection. While at it also fix up the same call
in drm_dp_mst_dump_topology().

Cc: Lyude Paul <lyude@redhat.com>
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/5292
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Cc: <stable@vger.kernel.org> # v5.14+
Reviewed-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220614094537.885472-1-imre.deak@intel.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index b3e3bab..2a586e6 100644 (file)
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -3860,9 +3860,7 @@ int drm_dp_mst_topology_mgr_resume(struct drm_dp_mst_topology_mgr *mgr,
        if (!mgr->mst_primary)
                goto out_fail;
 
-       ret = drm_dp_dpcd_read(mgr->aux, DP_DPCD_REV, mgr->dpcd,
-                              DP_RECEIVER_CAP_SIZE);
-       if (ret != DP_RECEIVER_CAP_SIZE) {
+       if (drm_dp_read_dpcd_caps(mgr->aux, mgr->dpcd) < 0) {
                drm_dbg_kms(mgr->dev, "dpcd read failed - undocked during suspend?\n");
                goto out_fail;
        }
@@ -4894,8 +4892,7 @@ void drm_dp_mst_dump_topology(struct seq_file *m,
                u8 buf[DP_PAYLOAD_TABLE_SIZE];
                int ret;
 
-               ret = drm_dp_dpcd_read(mgr->aux, DP_DPCD_REV, buf, DP_RECEIVER_CAP_SIZE);
-               if (ret) {
+               if (drm_dp_read_dpcd_caps(mgr->aux, buf) < 0) {
                        seq_printf(m, "dpcd read failed\n");
                        goto out;
                }