drm/virtgpu: initialise fbdev after getting initial display info

This should avoid issues with the fbdev path trying to render
before we've gotten the display info.
Signed-off-by: Dave Airlie <airlied@redhat.com>

[ kraxel: wait for display-info reply ]
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

drivers/gpu/drm/virtio/virtgpu_drv.h

@@ -171,6 +171,7 @@ struct virtio_gpu_device {
 	wait_queue_head_t resp_wq;
 	/* current display info */
 	spinlock_t display_info_lock;
+	bool display_info_pending;
 
 	struct virtio_gpu_fence_driver fence_drv;
 

drivers/gpu/drm/virtio/virtgpu_kms.c

@@ -137,9 +137,11 @@ int virtio_gpu_driver_load(struct drm_device *dev, unsigned long flags)
 	virtio_device_ready(vgdev->vdev);
 	vgdev->vqs_ready = true;
 
+	virtio_gpu_cmd_get_display_info(vgdev);
+	wait_event_timeout(vgdev->resp_wq, !vgdev->display_info_pending,
+			   5 * HZ);
 	if (virtio_gpu_fbdev)
 		virtio_gpu_fbdev_init(vgdev);
-	virtio_gpu_cmd_get_display_info(vgdev);
 
 	return 0;
 

drivers/gpu/drm/virtio/virtgpu_vq.c

@@ -534,6 +534,7 @@ static void virtio_gpu_cmd_get_display_info_cb(struct virtio_gpu_device *vgdev,
 		}
 	}
 
+	vgdev->display_info_pending = false;
 	spin_unlock(&vgdev->display_info_lock);
 	wake_up(&vgdev->resp_wq);
 
@@ -558,6 +559,7 @@ int virtio_gpu_cmd_get_display_info(struct virtio_gpu_device *vgdev)
 		 resp_buf);
 	memset(cmd_p, 0, sizeof(*cmd_p));
 
+	vgdev->display_info_pending = true;
 	cmd_p->type = cpu_to_le32(VIRTIO_GPU_CMD_GET_DISPLAY_INFO);
 	virtio_gpu_queue_ctrl_buffer(vgdev, vbuf);
 	return 0;