drm/i915: Set two chicken bits implicated in missed IRQs on Ivybridge.

They don't fix our problems alone, but we're told to set them.

Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Keith Packard <keithp@keithp.com>
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index eb44432..edced95 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -3020,6 +3020,10 @@
 #define   ILK_DPFC_DIS1		(1<<8)
 #define   ILK_DPFC_DIS2		(1<<9)
 
+#define IVB_CHICKEN3	0x4200c
+# define CHICKEN3_DGMG_REQ_OUT_FIX_DISABLE	(1 << 5)
+# define CHICKEN3_DGMG_DONE_FIX_DISABLE		(1 << 2)
+
 #define DISP_ARB_CTL	0x45000
 #define  DISP_TILE_SURFACE_SWIZZLING	(1<<13)
 #define  DISP_FBC_WM_DIS		(1<<15)