drm/i915/bdw: Implement ff workarounds

WaVSRefCountFullforceMissDisable and
WaDSRefCountFullforceMissDisable

VS is a carry-over from HSW, and DS is likely not used by anyone yet.

Cc: Kenneth Graunke <kenneth@whitecape.org>
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NDamien Lespiau <damien.lespiau@intel.com>
[danvet: Line of 106 chars is too long. Really.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_reg.h

@@ -1003,6 +1003,7 @@
 
 #define GEN7_FF_THREAD_MODE		0x20a0
 #define   GEN7_FF_SCHED_MASK		0x0077070
+#define   GEN8_FF_DS_REF_CNT_FFME	(1 << 19)
 #define   GEN7_FF_TS_SCHED_HS1		(0x5<<16)
 #define   GEN7_FF_TS_SCHED_HS0		(0x3<<16)
 #define   GEN7_FF_TS_SCHED_LOAD_BALANCE	(0x1<<16)

drivers/gpu/drm/i915/intel_pm.c

@@ -5256,14 +5256,14 @@ static void gen8_init_clock_gating(struct drm_device *dev)
 	I915_WRITE(GEN7_HALF_SLICE_CHICKEN1,
 		   _MASKED_BIT_ENABLE(GEN7_SINGLE_SUBSCAN_DISPATCH_ENABLE));
 
-	/* WaSwitchSolVfFArbitrationPriority */
+	/* WaSwitchSolVfFArbitrationPriority:bdw */
 	I915_WRITE(GAM_ECOCHK, I915_READ(GAM_ECOCHK) | HSW_ECOCHK_ARB_PRIO_SOL);
 
-	/* WaPsrDPAMaskVBlankInSRD */
+	/* WaPsrDPAMaskVBlankInSRD:bdw */
 	I915_WRITE(CHICKEN_PAR1_1,
 		   I915_READ(CHICKEN_PAR1_1) | DPA_MASK_VBLANK_SRD);
 
-	/* WaPsrDPRSUnmaskVBlankInSRD */
+	/* WaPsrDPRSUnmaskVBlankInSRD:bdw */
 	for_each_pipe(i) {
 		I915_WRITE(CHICKEN_PIPESL_1(i),
 			   I915_READ(CHICKEN_PIPESL_1(i) |
@@ -5277,6 +5277,12 @@ static void gen8_init_clock_gating(struct drm_device *dev)
 	I915_WRITE(HDC_CHICKEN0,
 		   I915_READ(HDC_CHICKEN0) |
 		   _MASKED_BIT_ENABLE(HDC_FORCE_NON_COHERENT));
+
+	/* WaVSRefCountFullforceMissDisable:bdw */
+	/* WaDSRefCountFullforceMissDisable:bdw */
+	I915_WRITE(GEN7_FF_THREAD_MODE,
+		   I915_READ(GEN7_FF_THREAD_MODE) &
+		   ~(GEN8_FF_DS_REF_CNT_FFME | GEN7_FF_VS_REF_CNT_FFME));
 }
 
 static void haswell_init_clock_gating(struct drm_device *dev)