drm/atomic: Refcounting for plane_state->fb

[firefly-linux-kernel-4.4.55.git] / drivers / gpu / drm / drm_atomic.c

diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index ad15a88c0f7476794f9a65a3d9d42ef1c0da7518..ed991ba66e21932c66ff828334dfba1bb343865a 100644 (file)
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -367,6 +367,34 @@ drm_atomic_set_crtc_for_plane(struct drm_plane_state *plane_state,
 }
 EXPORT_SYMBOL(drm_atomic_set_crtc_for_plane);
 
+/**
+ * drm_atomic_set_fb_for_plane - set crtc for plane
+ * @plane_state: atomic state object for the plane
+ * @fb: fb to use for the plane
+ *
+ * Changing the assigned framebuffer for a plane requires us to grab a reference
+ * to the new fb and drop the reference to the old fb, if there is one. This
+ * function takes care of all these details besides updating the pointer in the
+ * state object itself.
+ */
+void
+drm_atomic_set_fb_for_plane(struct drm_plane_state *plane_state,
+                           struct drm_framebuffer *fb)
+{
+       if (plane_state->fb)
+               drm_framebuffer_unreference(plane_state->fb);
+       if (fb)
+               drm_framebuffer_reference(fb);
+       plane_state->fb = fb;
+
+       if (fb)
+               DRM_DEBUG_KMS("Set [FB:%d] for plane state %p\n",
+                             fb->base.id, plane_state);
+       else
+               DRM_DEBUG_KMS("Set [NOFB] for plane state %p\n", plane_state);
+}
+EXPORT_SYMBOL(drm_atomic_set_fb_for_plane);
+
 /**
  * drm_atomic_set_crtc_for_connector - set crtc for connector
  * @conn_state: atomic state object for the connector