Commit 2e0a5765 authored Feb 13, 2020 by Jani Nikula

drm/i915/dsc: force full modeset whenever DSC is enabled at probe

We lack full state readout of DSC config, which may lead to DSC enable
using a config that's all zeros, failing spectacularly. Force full
modeset and thus compute config at probe to get a sane state, until we
implement DSC state readout. Any fastset that did appear to work with
DSC at probe, worked by coincidence. [1] is an example of a change that
triggered the issue on TGL DSI DSC.

[1] http://patchwork.freedesktop.org/patch/msgid/20200212150102.7600-1-ville.syrjala@linux.intel.com



Cc: Manasi Navare <manasi.d.navare@intel.com>
Cc: Vandita Kulkarni <vandita.kulkarni@intel.com>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: stable@vger.kernel.org
Fixes: fbacb15e ("drm/i915/dsc: add basic hardware state readout support")
Acked-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200213140412.32697-3-stanislav.lisovskiy@intel.com


(cherry picked from commit a4277aa3)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

parent 58e9121c

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

+18 −0

Original line number	Diff line number	Diff line
		@@ -17433,6 +17433,24 @@ retry:
		* have readout for pipe gamma enable.
		*/
		crtc_state->uapi.color_mgmt_changed = true;

		/*
		* FIXME hack to force full modeset when DSC is being
		* used.
		*
		* As long as we do not have full state readout and
		* config comparison of crtc_state->dsc, we have no way
		* to ensure reliable fastset. Remove once we have
		* readout for DSC.
		*/
		if (crtc_state->dsc.compression_enable) {
		ret = drm_atomic_add_affected_connectors(state,
		&crtc->base);
		if (ret)
		goto out;
		crtc_state->uapi.mode_changed = true;
		drm_dbg_kms(dev, "Force full modeset for DSC\n");
		}
		}
		}

Admin message