From: Chris Wilson <chris@chris-wilson.co.uk>

Subject: i915: Debug test patch to see why i915_gem_map_gtt fails

[ dileks: v2: Adapt to fit drm-intel-nightly pulled into next-20130725. ]

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 340d547..efb364e 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1535,24 +1535,29 @@ i915_gem_mmap_gtt(struct drm_file *file,
 
 	obj = to_intel_bo(drm_gem_object_lookup(dev, file, handle));
 	if (&obj->base == NULL) {
+		DRM_DRIVER_DEBUG("Unknown object handle %d\n", handle);
 		ret = -ENOENT;
 		goto unlock;
 	}
 
 	if (obj->base.size > dev_priv->gtt.mappable_end) {
+		DRM_DRIVER_DEBUG("Object (%d) larger than mappable aperture (%d) > %d\n",
+				(int)obj->base.size, (int)dev_priv->gtt.mappable_end);
 		ret = -E2BIG;
 		goto out;
 	}
 
 	if (obj->madv != I915_MADV_WILLNEED) {
-		DRM_ERROR("Attempting to mmap a purgeable buffer\n");
+		DRM_DRIVER_DEBUG("Attempting to mmap a purgeable buffer\n");
 		ret = -EINVAL;
 		goto out;
 	}
 
 	ret = i915_gem_object_create_mmap_offset(obj);
-	if (ret)
+	if (ret) {
+		DRM_DRIVER_DEBUG("Failed to allocate mmap offset (ret=%d)\n", ret);
 		goto out;
+	}
 
 	*offset = drm_vma_node_offset_addr(&obj->base.vma_node);