Revert "drm/i915: Display WA #1133 WaFbcSkipSegments:cnl, glk"

This reverts commit 8f067837c4b713ce2e69be95af7b2a5eb3bd7de8.

HSD says "WA withdrawn. It was causing corruption with some images.
WA is not strictly necessary since this bug just causes loss of FBC
compression with some sizes and images, but doesn't break anything."

Fixes: 8f067837c4b7 ("drm/i915: Display WA #1133 WaFbcSkipSegments:cnl, glk")
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171117010825.23118-1-radhakrishna.sripada@intel.com
(cherry picked from commit 0cfecb7c4b9b45ed1776162e132b43f92564f3f4)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

drivers/gpu/drm/i915/i915_reg.h

@@ -2951,9 +2951,6 @@ enum i915_power_well_id {
 #define ILK_DPFC_CHICKEN	_MMIO(0x43224)
 #define   ILK_DPFC_DISABLE_DUMMY0 (1<<8)
 #define   ILK_DPFC_NUKE_ON_ANY_MODIFICATION	(1<<23)
-#define   GLK_SKIP_SEG_EN		(1<<12)
-#define   GLK_SKIP_SEG_COUNT_MASK	(3<<10)
-#define   GLK_SKIP_SEG_COUNT(x)		((x)<<10)
 #define ILK_FBC_RT_BASE		_MMIO(0x2128)
 #define   ILK_FBC_RT_VALID	(1<<0)
 #define   SNB_FBC_FRONT_BUFFER	(1<<1)

drivers/gpu/drm/i915/intel_pm.c

@@ -124,7 +124,6 @@ static void bxt_init_clock_gating(struct drm_i915_private *dev_priv)
 
 static void glk_init_clock_gating(struct drm_i915_private *dev_priv)
 {
-	u32 val;
 	gen9_init_clock_gating(dev_priv);
 
 	/*
@@ -144,11 +143,6 @@ static void glk_init_clock_gating(struct drm_i915_private *dev_priv)
 		I915_WRITE(CHICKEN_MISC_2, val);
 	}
 
-	/* Display WA #1133: WaFbcSkipSegments:glk */
-	val = I915_READ(ILK_DPFC_CHICKEN);
-	val &= ~GLK_SKIP_SEG_COUNT_MASK;
-	val |= GLK_SKIP_SEG_EN | GLK_SKIP_SEG_COUNT(1);
-	I915_WRITE(ILK_DPFC_CHICKEN, val);
 }
 
 static void i915_pineview_get_mem_freq(struct drm_i915_private *dev_priv)
@@ -8517,7 +8511,6 @@ static void cnp_init_clock_gating(struct drm_i915_private *dev_priv)
 
 static void cnl_init_clock_gating(struct drm_i915_private *dev_priv)
 {
-	u32 val;
 	cnp_init_clock_gating(dev_priv);
 
 	/* This is not an Wa. Enable for better image quality */
@@ -8537,12 +8530,6 @@ static void cnl_init_clock_gating(struct drm_i915_private *dev_priv)
 		I915_WRITE(SLICE_UNIT_LEVEL_CLKGATE,
 			   I915_READ(SLICE_UNIT_LEVEL_CLKGATE) |
 			   SARBUNIT_CLKGATE_DIS);
-
-	/* Display WA #1133: WaFbcSkipSegments:cnl */
-	val = I915_READ(ILK_DPFC_CHICKEN);
-	val &= ~GLK_SKIP_SEG_COUNT_MASK;
-	val |= GLK_SKIP_SEG_EN | GLK_SKIP_SEG_COUNT(1);
-	I915_WRITE(ILK_DPFC_CHICKEN, val);
 }
 
 static void cfl_init_clock_gating(struct drm_i915_private *dev_priv)