drm/i915: Clarify WaDisable4x2SubspanOptimization situation for VLV
WaDisable4x2SubspanOptimization isn't listed for VLV in the workaround
database, but BSpec says that the relevant bit must be set. Add a
comment to remind people of this.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 6c435e4..cb96b0a 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -4945,6 +4945,10 @@
I915_WRITE(MI_ARB_VLV, MI_ARB_DISPLAY_TRICKLE_FEED_DISABLE);
+ /*
+ * BSpec says this must be set, even though
+ * WaDisable4x2SubspanOptimization isn't listed for VLV.
+ */
I915_WRITE(CACHE_MODE_1,
_MASKED_BIT_ENABLE(PIXEL_SUBSPAN_COLLECT_OPT_DISABLE));