drm/i915: We implement WaFbcAsynchFlipDisableFbcQueue on ilk and snb

v2: Put the comment a bit closer to the actual write (Paulo Zanoni)
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
[danvet: Fix space before tab.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_pm.c

@@ -4453,6 +4453,7 @@ static void ironlake_init_clock_gating(struct drm_device *dev)
 	 * The bit 7,8,9 of 0x42020.
 	 */
 	if (IS_IRONLAKE_M(dev)) {
+		/* WaFbcAsynchFlipDisableFbcQueue:ilk */
 		I915_WRITE(ILK_DISPLAY_CHICKEN1,
 			   I915_READ(ILK_DISPLAY_CHICKEN1) |
 			   ILK_FBCQ_DIS);
@@ -4589,6 +4590,8 @@ static void gen6_init_clock_gating(struct drm_device *dev)
 	 * The bit5 and bit7 of 0x42020
 	 * The bit14 of 0x70180
 	 * The bit14 of 0x71180
+	 *
+	 * WaFbcAsynchFlipDisableFbcQueue:snb
 	 */
 	I915_WRITE(ILK_DISPLAY_CHICKEN1,
 		   I915_READ(ILK_DISPLAY_CHICKEN1) |