[PATCH 5.18 0983/1095] drm/dp/mst: Read the extended DPCD capabilities during system resume

Greg Kroah-Hartman
2022-08-15T23:14:49Z

From: Imre Deak <imre.deak@intel.com>

[ 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>
---
drivers/gpu/drm/dp/drm_dp_mst_topology.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/dp/drm_dp_mst_topology.c b/drivers/gpu/drm/dp/drm_dp_mst_topology.c
index 7a7cc44686f9..96869875390f 100644
--- a/drivers/gpu/drm/dp/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/dp/drm_dp_mst_topology.c
@@ -3861,9 +3861,7 @@ 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;
}
@@ -4912,8 +4910,7 @@ 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;
}
--
2.35.1