[PATCH 18/26] drm/i915/dp_mst: Enable DSC decompression if any stream needs this

[Imre Deak]

Atm DSC decompression is enabled in the sink only if the first stream is
compressed. This left compressed streams blank if the first stream was
uncompressed.

Enable decompression whenever FEC is enabled, which will be true for all
streams if any stream is compressed. Enabling FEC correctly in all
streams will be only fixed by an upcoming patch.

Signed-off-by: Imre Deak <imre.deak at intel.com>
---
 drivers/gpu/drm/i915/display/intel_dp.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 2053b1a26c9b2..e40c7211e2427 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -2909,7 +2909,13 @@ void intel_dp_sink_set_decompression_state(struct intel_dp *intel_dp,
 	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
 	int ret;
 
-	if (!crtc_state->dsc.compression_enable)
+	/*
+	 * In case of MST any stream can be compressed not just the first. If
+	 * any stream is compressed FEC will be enabled in all streams, so toggle
+	 * decompression whenever FEC is enabled.
+	 */
+	if (!crtc_state->dsc.compression_enable &&
+	    !crtc_state->fec_enable)
 		return;
 
 	ret = drm_dp_dpcd_writeb(&intel_dp->aux, DP_DSC_ENABLE,
-- 
2.37.2