[Intel-gfx] [PATCH 3/3] drm/i915: Implement new w/a for underruns with wm1+ disabled

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

The new workaround from the hw team involves programming the
leaving WM1 still disabled but programming the blocks value
identically to WM0, and we also need to set the "ignore
lines watermark" bit for WM1.

Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/intel_pm.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 7dd2ab0ca21b..4c0e43caa5cd 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -4466,6 +4466,13 @@ skl_allocate_pipe_ddb(struct intel_crtc_state *cstate,
 		for_each_plane_id_on_crtc(intel_crtc, plane_id) {
 			wm = &cstate->wm.skl.optimal.planes[plane_id];
 			memset(&wm->wm[level], 0, sizeof(wm->wm[level]));
+
+			/* W/A for underruns with WM1+ disabled */
+			if (IS_ICELAKE(dev_priv) &&
+			    level == 1 && wm->wm[0].plane_en) {
+				wm->wm[level].plane_res_b = wm->wm[0].plane_res_b;
+				wm->wm[level].ignore_lines = true;
+			}
 		}
 	}
 
-- 
2.19.2