[Intel-gfx] [PATCH] drm/i915: Implement workaround for DP2 UHBR bandwidth check

[Stanislav Lisovskiy]

According to spec, we should check if output_bpp * pixel_rate is less
than DDI clock * 72, if UHBR is used.

Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com>
---
 drivers/gpu/drm/i915/display/intel_dp.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index bf80f296a8fdb..13baf3cb5f934 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -1582,6 +1582,17 @@ int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
 		drm_dbg_kms(&dev_priv->drm, "DSC: compressed bpp %d slice count %d\n",
 			    pipe_config->dsc.compressed_bpp,
 			    pipe_config->dsc.slice_count);
+
+		/* wa1406899791 */
+		if (intel_dp_is_uhbr(pipe_config)) {
+			int output_bpp = pipe_config->dsc.compressed_bpp;
+
+			if (output_bpp * adjusted_mode->crtc_clock >=
+			    pipe_config->port_clock * 72) {
+				drm_dbg_kms(&dev_priv->drm, "DP2 UHBR check failed\n");
+				return -EINVAL;
+			}
+		}
 	}
 	/*
 	 * VDSC engine operates at 1 Pixel per clock, so if peak pixel rate
-- 
2.37.3