From c8e8e9ab14a6ea926641d161768e1e3ef286a853 Mon Sep 17 00:00:00 2001 From: Suraj Kandpal Date: Mon, 8 Sep 2025 09:52:08 +0530 Subject: [PATCH] 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: 6671c367a9bea ("drm/i915/tgl: Select master transcoder for MST stream") Signed-off-by: Suraj Kandpal Reviewed-by: Jani Nikula Link: https://lore.kernel.org/r/20250908042208.1011144-1-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 08083ac83a74f..c09aa759f4d4f 100644 --- a/drivers/gpu/drm/i915/display/intel_ddi.c +++ b/drivers/gpu/drm/i915/display/intel_ddi.c @@ -597,8 +597,9 @@ 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 { -- 2.47.3