[Intel-gfx] [PATCH v2] drm/i915/fbc: Disable fbc with VT-d also with cometlake

[Lee Shawn C]

Both VT-d and FBC enabled that caused display flicker
issue very randomly. According to sighting report,
it recommend to disable FBC to workaround this issue.

v2: Specific this change for CML U series device.
    Using IS_CML_ULT() instead of IS_COMETLAKE().

Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
Cc: Jani Nikula <jani.nikula at intel.com>
Cc: William Tseng <william.tseng at intel.com>
Signed-off-by: Lee Shawn C <shawn.c.lee at intel.com>
---
 drivers/gpu/drm/i915/display/intel_fbc.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_fbc.c b/drivers/gpu/drm/i915/display/intel_fbc.c
index 135f5e8a4d70..c99c4c84a0ed 100644
--- a/drivers/gpu/drm/i915/display/intel_fbc.c
+++ b/drivers/gpu/drm/i915/display/intel_fbc.c
@@ -1443,7 +1443,9 @@ static bool need_fbc_vtd_wa(struct drm_i915_private *dev_priv)
 {
 	/* WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl,bxt */
 	if (intel_vtd_active() &&
-	    (IS_SKYLAKE(dev_priv) || IS_BROXTON(dev_priv))) {
+	    (IS_SKYLAKE(dev_priv) ||
+	     IS_BROXTON(dev_priv) ||
+	     IS_CML_ULT(dev_priv))) {
 		drm_info(&dev_priv->drm,
 			 "Disabling framebuffer compression (FBC) to prevent screen flicker with VT-d enabled\n");
 		return true;
-- 
2.17.1