drm/i915: handle interrupt on new chipset

Update interrupt handling methods for IGDNG with new registers
for display and graphics interrupt functions. As we won't use
irq-based vblank sync in dri2, so display interrupt on new chip
will be used for hotplug only in future.

Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 3fbd8a0..38e0f83 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1714,7 +1714,10 @@
 	BUG_ON(seqno == 0);
 
 	if (!i915_seqno_passed(i915_get_gem_seqno(dev), seqno)) {
-		ier = I915_READ(IER);
+		if (IS_IGDNG(dev))
+			ier = I915_READ(DEIER) | I915_READ(GTIER);
+		else
+			ier = I915_READ(IER);
 		if (!ier) {
 			DRM_ERROR("something (likely vbetool) disabled "
 				  "interrupts, re-enabling\n");