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* [PATCH v2] drm/i915/ddi: Guard reg_val against a INVALID_TRANSCODER
@ 2025-09-08  4:22 Suraj Kandpal
  2025-09-08  4:29 ` ✓ CI.KUnit: success for drm/i915/ddi: Guard reg_val against a INVALID_TRANSCODER (rev2) Patchwork
                   ` (3 more replies)
  0 siblings, 4 replies; 5+ messages in thread
From: Suraj Kandpal @ 2025-09-08  4:22 UTC (permalink / raw)
  To: intel-xe, intel-gfx; +Cc: jani.nikula, ankit.k.nautiyal, Suraj Kandpal

Currently we check if the encoder is INVALID or -1 and throw a
WARN_ON but we still end up writing the temp value which will
overflow and corrupt the whole programmed value.

--v2
-Assign a bogus transcoder to master in case we get a INVALID
TRANSCODER [Jani]

Fixes: 6671c367a9bea ("drm/i915/tgl: Select master transcoder for MST stream")
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
---
 drivers/gpu/drm/i915/display/intel_ddi.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
index 46017091bb0b..f67ce35c1c00 100644
--- a/drivers/gpu/drm/i915/display/intel_ddi.c
+++ b/drivers/gpu/drm/i915/display/intel_ddi.c
@@ -596,8 +596,9 @@ intel_ddi_transcoder_func_reg_val_get(struct intel_encoder *encoder,
 			enum transcoder master;
 
 			master = crtc_state->mst_master_transcoder;
-			drm_WARN_ON(display->drm,
-				    master == INVALID_TRANSCODER);
+			if (drm_WARN_ON(display->drm,
+					master == INVALID_TRANSCODER))
+				master = TRANSCODER_A;
 			temp |= TRANS_DDI_MST_TRANSPORT_SELECT(master);
 		}
 	} else {
-- 
2.34.1


^ permalink raw reply related	[flat|nested] 5+ messages in thread
end of thread, other threads:[~2025-09-19 10:27 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
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2025-09-08  4:22 [PATCH v2] drm/i915/ddi: Guard reg_val against a INVALID_TRANSCODER Suraj Kandpal
2025-09-08  4:29 ` ✓ CI.KUnit: success for drm/i915/ddi: Guard reg_val against a INVALID_TRANSCODER (rev2) Patchwork
2025-09-08  5:03 ` ✓ Xe.CI.BAT: " Patchwork
2025-09-08  6:11 ` ✓ Xe.CI.Full: " Patchwork
2025-09-19 10:27 ` [PATCH v2] drm/i915/ddi: Guard reg_val against a INVALID_TRANSCODER Jani Nikula

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