drm/i915: implement WaDisableDopClockGatingisable on VLV and IVB

v2: use correct register
v3: remove extra hunks, pull in register definitions & offset check directly
v4: add GT1 vs GT2 distinction for IVB portion (Ben)

References: https://bugs.freedesktop.org/show_bug.cgi?id=50233Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: Antti Koskipää <antti.koskipaa@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.c

@@ -1132,6 +1132,13 @@ static bool IS_DISPLAYREG(u32 reg)
 	if (reg == GEN6_GDRST)
 		return false;
 
+	switch (reg) {
+	case GEN7_ROW_CHICKEN2:
+		return false;
+	default:
+		break;
+	}
+
 	return true;
 }
 

drivers/gpu/drm/i915/i915_drv.h

@@ -1125,6 +1125,9 @@ struct drm_i915_file_private {
 #define IS_IRONLAKE_D(dev)	((dev)->pci_device == 0x0042)
 #define IS_IRONLAKE_M(dev)	((dev)->pci_device == 0x0046)
 #define IS_IVYBRIDGE(dev)	(INTEL_INFO(dev)->is_ivybridge)
+#define IS_IVB_GT1(dev)		((dev)->pci_device == 0x0156 || \
+				 (dev)->pci_device == 0x0152 ||	\
+				 (dev)->pci_device == 0x015a)
 #define IS_VALLEYVIEW(dev)	(INTEL_INFO(dev)->is_valleyview)
 #define IS_HASWELL(dev)	(INTEL_INFO(dev)->is_haswell)
 #define IS_MOBILE(dev)		(INTEL_INFO(dev)->is_mobile)

drivers/gpu/drm/i915/i915_reg.h

@@ -4303,6 +4303,10 @@
 #define GEN7_L3LOG_BASE			0xB070
 #define GEN7_L3LOG_SIZE			0x80
 
+#define GEN7_ROW_CHICKEN2		0xe4f4
+#define GEN7_ROW_CHICKEN2_GT2		0xf4f4
+#define   DOP_CLOCK_GATING_DISABLE	(1<<0)
+
 #define G4X_AUD_VID_DID			0x62020
 #define INTEL_AUDIO_DEVCL		0x808629FB
 #define INTEL_AUDIO_DEVBLC		0x80862801

drivers/gpu/drm/i915/intel_pm.c

@@ -3601,6 +3601,13 @@ static void ivybridge_init_clock_gating(struct drm_device *dev)
 			GEN7_WA_FOR_GEN7_L3_CONTROL);
 	I915_WRITE(GEN7_L3_CHICKEN_MODE_REGISTER,
 		   GEN7_WA_L3_CHICKEN_MODE);
+	if (IS_IVB_GT1(dev))
+		I915_WRITE(GEN7_ROW_CHICKEN2,
+			   _MASKED_BIT_ENABLE(DOP_CLOCK_GATING_DISABLE));
+	else
+		I915_WRITE(GEN7_ROW_CHICKEN2_GT2,
+			   _MASKED_BIT_ENABLE(DOP_CLOCK_GATING_DISABLE));
+
 
 	/* WaForceL3Serialization */
 	I915_WRITE(GEN7_L3SQCREG4, I915_READ(GEN7_L3SQCREG4) &
@@ -3684,6 +3691,10 @@ static void valleyview_init_clock_gating(struct drm_device *dev)
 	I915_WRITE(GEN7_L3SQCREG4, I915_READ(GEN7_L3SQCREG4) &
 		   ~L3SQ_URB_READ_CAM_MATCH_DISABLE);
 
+	/* WaDisableDopClockGating */
+	I915_WRITE(GEN7_ROW_CHICKEN2,
+		   _MASKED_BIT_ENABLE(DOP_CLOCK_GATING_DISABLE));
+
 	/* This is required by WaCatErrorRejectionIssue */
 	I915_WRITE(GEN7_SQ_CHICKEN_MBCUNIT_CONFIG,
 		   I915_READ(GEN7_SQ_CHICKEN_MBCUNIT_CONFIG) |