drm/i915/gen9: Add WaFbcHighMemBwCorruptionAvoidance

Add this fbc related workaround for all gen9

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1465309159-30531-28-git-send-email-mika.kuoppala@intel.com
(cherry picked from commit d1b4eefdea6d63aa15321f539feec298d8aefdc1)
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 3b37428..b2fbbfa 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -2206,6 +2206,7 @@
 #define ILK_DPFC_STATUS		_MMIO(0x43210)
 #define ILK_DPFC_FENCE_YOFF	_MMIO(0x43218)
 #define ILK_DPFC_CHICKEN	_MMIO(0x43224)
+#define   ILK_DPFC_DISABLE_DUMMY0 (1<<8)
 #define   ILK_DPFC_NUKE_ON_ANY_MODIFICATION	(1<<23)
 #define ILK_FBC_RT_BASE		_MMIO(0x2128)
 #define   ILK_FBC_RT_VALID	(1<<0)
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 074d6a5..2863b92 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -74,6 +74,10 @@
 	I915_WRITE(DISP_ARB_CTL, I915_READ(DISP_ARB_CTL) |
 		   DISP_FBC_WM_DIS |
 		   DISP_FBC_MEMORY_WAKE);
+
+	/* WaFbcHighMemBwCorruptionAvoidance:skl,bxt,kbl */
+	I915_WRITE(ILK_DPFC_CHICKEN, I915_READ(ILK_DPFC_CHICKEN) |
+		   ILK_DPFC_DISABLE_DUMMY0);
 }
 
 static void bxt_init_clock_gating(struct drm_device *dev)