Commit ab67821f authored by Imre Deak's avatar Imre Deak
Browse files

drm/i915/dp_mst: Disable DSC on ICL MST outputs 

Enabling DSC on ICL MST outputs is broken leading to FIFO pipe /
transcoder underruns and blank screen. On TGL+ platforms MST/DSC works -
after fixing the known issues in [1] - however to make this work on ICL
requires more work.

So far DSC on MST probably didn't get enabled for users - due to an issue
fixed by [2] - but after fixing that, DSC could get enabled, leading to a
blank screen in ICL/MST configurations which do work atm. To prevent
this disable MST/DSC on ICL for now.

[1] https://lore.kernel.org/all/20231030155843.2251023-1-imre.deak@intel.com
[2] https://lore.kernel.org/all/20231030155843.2251023-31-imre.deak@intel.com



v2 (Ville):
- Use DISPLAY_VER >= 12 instead of > 11.
- Explain the ICL DSC issue in code comment.

Cc: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: default avatarImre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231102194434.2634786-1-imre.deak@intel.com
parent 70a3cbbe

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

+16 −0
Original line number Diff line number Diff line
@@ -43,6 +43,7 @@ 
#include "intel_dpio_phy.h"

#include "intel_hdcp.h"

#include "intel_hotplug.h"

#include "intel_vdsc.h"

#include "skl_scaler.h"



static int intel_dp_mst_check_constraints(struct drm_i915_private *i915, int bpp,
@@ -297,6 +298,18 @@ static int intel_dp_mst_update_slots(struct intel_encoder *encoder, 
	return 0;

}



static bool

intel_dp_mst_dsc_source_support(const struct intel_crtc_state *crtc_state)

{

	struct drm_i915_private *i915 = to_i915(crtc_state->uapi.crtc->dev);



	/*

	 * FIXME: Enabling DSC on ICL results in blank screen and FIFO pipe /

	 * transcoder underruns, re-enable DSC after fixing this issue.

	 */

	return DISPLAY_VER(i915) >= 12 && intel_dsc_source_support(crtc_state);

}



static bool

intel_dp_mst_compute_config_limits(struct intel_dp *intel_dp,

				   struct intel_crtc_state *crtc_state,
@@ -375,6 +388,9 @@ static int intel_dp_mst_compute_config(struct intel_encoder *encoder, 
			    str_yes_no(ret),

			    str_yes_no(intel_dp->force_dsc_en));



		if (!intel_dp_mst_dsc_source_support(pipe_config))

			return -EINVAL;



		if (!intel_dp_mst_compute_config_limits(intel_dp,

							pipe_config,

							true,