Commit 6fd3134a authored Mar 26, 2019 by Ville Syrjälä

drm/i915: Do not enable FEC without DSC



Currently we enable FEC even when DSC is no used. While that is
theoretically valid supposedly there isn't much of a benefit from
this. But more importantly we do not account for the FEC link
bandwidth overhead (2.4%) in the non-DSC link bandwidth computations.
So the code may think we have enough bandwidth when we in fact
do not.

Cc: stable@vger.kernel.org
Cc: Anusha Srivatsa <anusha.srivatsa@intel.com>
Cc: Manasi Navare <manasi.d.navare@intel.com>
Fixes: 240999cf ("i915/dp/fec: Add fec_enable to the crtc state.")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190326144903.6617-1-ville.syrjala@linux.intel.com


Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>

parent 2e1e5c55

drivers/gpu/drm/i915/intel_dp.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -1895,6 +1895,9 @@ static int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
		int pipe_bpp;
		int ret;

		pipe_config->fec_enable = !intel_dp_is_edp(intel_dp) &&
		intel_dp_supports_fec(intel_dp, pipe_config);

		if (!intel_dp_supports_dsc(intel_dp, pipe_config))
		return -EINVAL;

		@@ -2156,9 +2159,6 @@ intel_dp_compute_config(struct intel_encoder *encoder,
		if (adjusted_mode->flags & DRM_MODE_FLAG_DBLCLK)
		return -EINVAL;

		pipe_config->fec_enable = !intel_dp_is_edp(intel_dp) &&
		intel_dp_supports_fec(intel_dp, pipe_config);

		ret = intel_dp_compute_link_config(encoder, pipe_config, conn_state);
		if (ret < 0)
		return ret;

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