virtio-gpu: fix output lookup

Needed for multihead setups where we can have disabled
outputs and therefore plane->crtc can be NULL.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1464609806-22013-1-git-send-email-kraxel@redhat.com

1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/gpu/drm/virtio/virtgpu_plane.c b/drivers/gpu/drm/virtio/virtgpu_plane.c
index 70b44a2345ab..e50674bccb09 100644
--- a/drivers/gpu/drm/virtio/virtgpu_plane.c
+++ b/drivers/gpu/drm/virtio/virtgpu_plane.c
@@ -63,11 +63,17 @@ static void virtio_gpu_plane_atomic_update(struct drm_plane *plane,
 {
         struct drm_device *dev = plane->dev;
         struct virtio_gpu_device *vgdev = dev->dev_private;
-        struct virtio_gpu_output *output = drm_crtc_to_virtio_gpu_output(plane->crtc);
+        struct virtio_gpu_output *output = NULL;
         struct virtio_gpu_framebuffer *vgfb;
         struct virtio_gpu_object *bo;
         uint32_t handle;
 
+        if (plane->state->crtc)
+                output = drm_crtc_to_virtio_gpu_output(plane->state->crtc);
+        if (old_state->crtc)
+                output = drm_crtc_to_virtio_gpu_output(old_state->crtc);
+        WARN_ON(!output);
+
         if (plane->state->fb) {
                 vgfb = to_virtio_gpu_framebuffer(plane->state->fb);
                 bo = gem_to_virtio_gpu_obj(vgfb->obj);