drm/i915: Remove WaFbcDisableDpfcClockGating on HSW

Production HSW does not need it. I confirmed this with Art.
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_reg.h

@@ -1106,9 +1106,6 @@
 					     _HSW_PIPE_SLICE_CHICKEN_1_A, + \
 					     _HSW_PIPE_SLICE_CHICKEN_1_B)
 
-#define HSW_CLKGATE_DISABLE_PART_1	0x46500
-#define   HSW_DPFC_GATING_DISABLE	(1<<23)
-
 /*
  * GPIO regs
  */

drivers/gpu/drm/i915/intel_pm.c

@@ -254,12 +254,6 @@ static void ironlake_disable_fbc(struct drm_device *dev)
 		dpfc_ctl &= ~DPFC_CTL_EN;
 		I915_WRITE(ILK_DPFC_CONTROL, dpfc_ctl);
 
-		if (IS_HASWELL(dev))
-			/* WaFbcDisableDpfcClockGating:hsw */
-			I915_WRITE(HSW_CLKGATE_DISABLE_PART_1,
-				   I915_READ(HSW_CLKGATE_DISABLE_PART_1) &
-				   ~HSW_DPFC_GATING_DISABLE);
-
 		DRM_DEBUG_KMS("disabled FBC\n");
 	}
 }
@@ -293,10 +287,6 @@ static void gen7_enable_fbc(struct drm_crtc *crtc, unsigned long interval)
 		/* WaFbcAsynchFlipDisableFbcQueue:hsw */
 		I915_WRITE(HSW_PIPE_SLICE_CHICKEN_1(intel_crtc->pipe),
 			   HSW_BYPASS_FBC_QUEUE);
-		/* WaFbcDisableDpfcClockGating:hsw */
-		I915_WRITE(HSW_CLKGATE_DISABLE_PART_1,
-			   I915_READ(HSW_CLKGATE_DISABLE_PART_1) |
-			   HSW_DPFC_GATING_DISABLE);
 	}
 
 	I915_WRITE(SNB_DPFC_CTL_SA,