drm/i915: Track pinned VMA

Treat the VMA as the primary struct responsible for tracking bindings
into the GPU's VM. That is we want to treat the VMA returned after we
pin an object into the VM as the cookie we hold and eventually release
when unpinning. Doing so eliminates the ambiguity in pinning the object
and then searching for the relevant pin later.

v2: Joonas' stylistic nitpicks, a fun rebase.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1471254551-25805-27-git-send-email-chris@chris-wilson.co.uk
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 9539f0e..1c700b0 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -193,6 +193,7 @@
 struct intel_fbdev {
 	struct drm_fb_helper helper;
 	struct intel_framebuffer *fb;
+	struct i915_vma *vma;
 	async_cookie_t cookie;
 	int preferred_bpp;
 };
@@ -1239,8 +1240,8 @@
 void intel_release_load_detect_pipe(struct drm_connector *connector,
 				    struct intel_load_detect_pipe *old,
 				    struct drm_modeset_acquire_ctx *ctx);
-int intel_pin_and_fence_fb_obj(struct drm_framebuffer *fb,
-			       unsigned int rotation);
+struct i915_vma *
+intel_pin_and_fence_fb_obj(struct drm_framebuffer *fb, unsigned int rotation);
 void intel_unpin_fb_obj(struct drm_framebuffer *fb, unsigned int rotation);
 struct drm_framebuffer *
 __intel_framebuffer_create(struct drm_device *dev,