Commit 7f97a0a8 authored by Suraj Kandpal's avatar Suraj Kandpal Committed by Tvrtko Ursulin
Browse files

drm/i915/ddi: Guard reg_val against a INVALID_TRANSCODER 



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: 6671c367 ("drm/i915/tgl: Select master transcoder for MST stream")
Signed-off-by: default avatarSuraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: default avatarJani Nikula <jani.nikula@intel.com>
Link: https://lore.kernel.org/r/20250908042208.1011144-1-suraj.kandpal@intel.com


(cherry picked from commit c8e8e9ab)
Signed-off-by: default avatarTvrtko Ursulin <tursulin@ursulin.net>
parent c1e72549

drivers/gpu/drm/i915/display/intel_ddi.c

+3 −2
Original line number Diff line number Diff line
@@ -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 {