drm/i915: fix ILK GPU reset for render

Earlier code would leave both bits set, so any reset after the first
would only reset media.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.c

@@ -744,6 +744,7 @@ static int ironlake_do_reset(struct drm_device *dev)
 	int ret;
 
 	gdrst = I915_READ(MCHBAR_MIRROR_BASE + ILK_GDSR);
+	gdrst &= ~GRDOM_MASK;
 	I915_WRITE(MCHBAR_MIRROR_BASE + ILK_GDSR,
 		   gdrst | GRDOM_RENDER | GRDOM_RESET_ENABLE);
 	ret = wait_for(I915_READ(MCHBAR_MIRROR_BASE + ILK_GDSR) & 0x1, 500);
@@ -752,6 +753,7 @@ static int ironlake_do_reset(struct drm_device *dev)
 
 	/* We can't reset render&media without also resetting display ... */
 	gdrst = I915_READ(MCHBAR_MIRROR_BASE + ILK_GDSR);
+	gdrst &= ~GRDOM_MASK;
 	I915_WRITE(MCHBAR_MIRROR_BASE + ILK_GDSR,
 		   gdrst | GRDOM_MEDIA | GRDOM_RESET_ENABLE);
 	return wait_for(I915_READ(MCHBAR_MIRROR_BASE + ILK_GDSR) & 0x1, 500);

drivers/gpu/drm/i915/i915_reg.h

@@ -91,6 +91,7 @@
 #define  GRDOM_FULL	(0<<2)
 #define  GRDOM_RENDER	(1<<2)
 #define  GRDOM_MEDIA	(3<<2)
+#define  GRDOM_MASK	(3<<2)
 #define  GRDOM_RESET_ENABLE (1<<0)
 
 #define GEN6_MBCUNIT_SNPCR	0x900c /* for LLC config */