stash: WA for SKL OA enabling (work-in-progress)

Author: rib

drivers/gpu/drm/i915/i915_perf.c

@@ -592,6 +592,9 @@ static void gen8_init_oa_buffer(struct drm_i915_private *dev_priv)
 {
 	I915_WRITE(GEN8_OAHEADPTR,
 		   dev_priv->perf.oa.oa_buffer.gtt_offset);
+
+	I915_WRITE(GEN8_OABUFFER_UDW, 0);
+
 	/* PRM says:
 	 *
 	 *  "This MMIO must be set before the OATAILPTR

drivers/gpu/drm/i915/i915_reg.h

@@ -626,6 +626,7 @@ static inline bool i915_mmio_reg_valid(i915_reg_t reg)
 #define  GEN7_OABUFFER_STOP_RESUME_ENABLE   (1<<1)
 #define  GEN7_OABUFFER_RESUME		    (1<<0)
 
+#define GEN8_OABUFFER_UDW _MMIO(0x23b4)
 #define GEN8_OABUFFER _MMIO(0x2b14)
 
 #define GEN7_OASTATUS1 _MMIO(0x2364)