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* [PATCH 1/2] drm/dp_mst: Fix GUID DPCD write to non-root MST branch devices
@ 2025-04-01 10:38 Imre Deak
  2025-04-01 10:38 ` [PATCH 2/2] drm/dp_mst: Use drm_dp_dpcd_write_data() to write GUID for " Imre Deak
                   ` (4 more replies)
  0 siblings, 5 replies; 7+ messages in thread
From: Imre Deak @ 2025-04-01 10:38 UTC (permalink / raw)
  To: intel-gfx, intel-xe; +Cc: dri-devel, Dmitry Baryshkov, Lyude Paul

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>
Signed-off-by: Imre Deak <imre.deak@intel.com>
---
 drivers/gpu/drm/display/drm_dp_mst_topology.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
index de3fc6090c906..619f461e02f76 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));
-- 
2.44.2


^ permalink raw reply related	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2025-04-03 18:50 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2025-04-01 10:38 [PATCH 1/2] drm/dp_mst: Fix GUID DPCD write to non-root MST branch devices Imre Deak
2025-04-01 10:38 ` [PATCH 2/2] drm/dp_mst: Use drm_dp_dpcd_write_data() to write GUID for " Imre Deak
2025-04-01 11:46 ` ✓ i915.CI.BAT: success for series starting with [1/2] drm/dp_mst: Fix GUID DPCD write to " Patchwork
2025-04-01 14:43 ` [PATCH 1/2] " Jani Nikula
2025-04-01 15:47 ` ✗ i915.CI.Full: failure for series starting with [1/2] " Patchwork
2025-04-03 18:49   ` Imre Deak
2025-04-02 21:13 ` [PATCH 1/2] " Lyude Paul

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