[Intel-gfx] [PATCH 21/23] drm/i915/gen9: Set fbc watermarks disabled

[Mika Kuoppala]

According to bspec this prevents screen corruption when fbc is
used.

References: HSD#2135555, HSD#2137270
Cc: Paulo Zanoni <paulo.r.zanoni at intel.com>
Signed-off-by: Mika Kuoppala <mika.kuoppala at intel.com>
---
 drivers/gpu/drm/i915/intel_pm.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 262180c0ba70..62734a16e873 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -67,6 +67,9 @@ static void gen9_init_clock_gating(struct drm_device *dev)
 
 	I915_WRITE(GEN8_CHICKEN_DCPR_1,
 		   I915_READ(GEN8_CHICKEN_DCPR_1) | MASK_WAKEMEM);
+
+	I915_WRITE(DISP_ARB_CTL,
+		   I915_READ(DISP_ARB_CTL) | DISP_FBC_WM_DIS);
 }
 
 static void bxt_init_clock_gating(struct drm_device *dev)
@@ -2798,7 +2801,7 @@ static void ilk_write_wm_values(struct drm_i915_private *dev_priv,
 
 	if (dirty & WM_DIRTY_FBC) {
 		val = I915_READ(DISP_ARB_CTL);
-		if (results->enable_fbc_wm)
+		if (!IS_GEN9(dev) && results->enable_fbc_wm)
 			val &= ~DISP_FBC_WM_DIS;
 		else
 			val |= DISP_FBC_WM_DIS;
-- 
2.5.0