diff options
| author | Imre Deak <imre.deak@intel.com> | 2025-04-01 13:38:45 +0300 |
|---|---|---|
| committer | Imre Deak <imre.deak@intel.com> | 2025-04-03 17:03:01 +0300 |
| commit | aea007741b951df05f901b2d4890df2e710d134b (patch) | |
| tree | 2e2e99f33c906360e28256ad65e72c5c1f5c1b99 /drivers/gpu/drm/display | |
| parent | 8abaa80b403e1fc40877eb9b339ae0ad07e8968f (diff) | |
drm/dp_mst: Fix GUID DPCD write to non-root MST branch devices
The return value on success of drm_dp_send_dpcd_write() called for
non-root MST branch devices from drm_dp_check_mstb_guid() is the number
of bytes transferred. Atm this return value (in case of a complete read)
will be regarded incorrectly as an error by the caller of
drm_dp_check_mstb_guid(). Fix this by converting the return value for a
complete read to the expected success code (0) and for a partial read to
a failure code (-EPROTO).
Fixes: 2554da0de3e8 ("drm/display: dp-mst-topology: use new DCPD access helpers")
Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc: Lyude Paul <lyude@redhat.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://lore.kernel.org/r/20250401103846.686408-1-imre.deak@intel.com
Diffstat (limited to 'drivers/gpu/drm/display')
| -rw-r--r-- | drivers/gpu/drm/display/drm_dp_mst_topology.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c index e8716e73480b..8c312c1f1724 100644 --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c @@ -2200,6 +2200,8 @@ static int drm_dp_check_mstb_guid(struct drm_dp_mst_branch *mstb, guid_t *guid) ret = drm_dp_send_dpcd_write(mstb->mgr, mstb->port_parent, DP_GUID, sizeof(buf), buf); + if (ret >= 0) + ret = ret == sizeof(buf) ? 0 : -EPROTO; } else { ret = drm_dp_dpcd_write_data(mstb->mgr->aux, DP_GUID, buf, sizeof(buf)); |