drm/i915: Shut down PCH interrupts during irq_uninstall

This masks out all interrupts and ack's any pending ones at IRQ
uninstall time to make sure we don't receive any unexpected interrupts
later on.
Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_irq.c

@@ -2044,6 +2044,10 @@ static void ironlake_irq_uninstall(struct drm_device *dev)
 	I915_WRITE(GTIMR, 0xffffffff);
 	I915_WRITE(GTIER, 0x0);
 	I915_WRITE(GTIIR, I915_READ(GTIIR));
+
+	I915_WRITE(SDEIMR, 0xffffffff);
+	I915_WRITE(SDEIER, 0x0);
+	I915_WRITE(SDEIIR, I915_READ(SDEIIR));
 }
 
 static void i915_driver_irq_uninstall(struct drm_device * dev)