drm/i915/gen9: Add WaFbcWakeMemOn

Set bit 8 in 0x43224 to prevent screen corruption and system
hangs on high memory bandwidth conditions. The same wa also suggest
setting bit 31 on ARB_CTL. According to another workaround we gain
better idle power savings when FBC is enabled.

v2: use correct workaround name
v3: split out overlapping wa for corruption avoidance (Ville)

References: HSD#2137218, HSD#2227171, HSD#2136579, BSID#883
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1465309159-30531-26-git-send-email-mika.kuoppala@intel.com

drivers/gpu/drm/i915/i915_reg.h

@@ -6054,6 +6054,7 @@ enum skl_disp_power_wells {
 #define CHICKEN_PIPESL_1(pipe) _MMIO_PIPE(pipe, _CHICKEN_PIPESL_1_A, _CHICKEN_PIPESL_1_B)
 
 #define DISP_ARB_CTL	_MMIO(0x45000)
+#define  DISP_FBC_MEMORY_WAKE		(1<<31)
 #define  DISP_TILE_SURFACE_SWIZZLING	(1<<13)
 #define  DISP_FBC_WM_DIS		(1<<15)
 #define DISP_ARB_CTL2	_MMIO(0x45004)

drivers/gpu/drm/i915/intel_pm.c

@@ -71,8 +71,10 @@ static void gen9_init_clock_gating(struct drm_device *dev)
 		   I915_READ(GEN8_CHICKEN_DCPR_1) | MASK_WAKEMEM);
 
 	/* WaFbcTurnOffFbcWatermark:skl,bxt,kbl */
-	I915_WRITE(DISP_ARB_CTL,
-		   I915_READ(DISP_ARB_CTL) | DISP_FBC_WM_DIS);
+	/* WaFbcWakeMemOn:skl,bxt,kbl */
+	I915_WRITE(DISP_ARB_CTL, I915_READ(DISP_ARB_CTL) |
+		   DISP_FBC_WM_DIS |
+		   DISP_FBC_MEMORY_WAKE);
 }
 
 static void bxt_init_clock_gating(struct drm_device *dev)