drm/i915: add GETPARAM request for page flipping

Add a GETPARAM request for checking if page flipping is supported.
Useful for the 2D driver to enable the flipping path.
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>

drivers/gpu/drm/i915/i915_dma.c

@@ -810,6 +810,9 @@ static int i915_getparam(struct drm_device *dev, void *data,
 	case I915_PARAM_HAS_OVERLAY:
 		value = dev_priv->overlay ? 1 : 0;
 		break;
+	case I915_PARAM_HAS_PAGEFLIPPING:
+		value = 1;
+		break;
 	default:
 		DRM_DEBUG_DRIVER("Unknown parameter %d\n",
 					param->param);

include/drm/i915_drm.h

@@ -271,6 +271,7 @@ typedef struct drm_i915_irq_wait {
 #define I915_PARAM_HAS_GEM               5
 #define I915_PARAM_NUM_FENCES_AVAIL      6
 #define I915_PARAM_HAS_OVERLAY           7
+#define I915_PARAM_HAS_PAGEFLIPPING	 8
 
 typedef struct drm_i915_getparam {
 	int param;