struct vivi_dev *dev = vb2_get_drv_priv(vq);
        unsigned long size;
 
-       size = dev->width * dev->height * dev->pixelsize;
+       if (fmt)
+               size = fmt->fmt.pix.sizeimage;
+       else
+               size = dev->width * dev->height * dev->pixelsize;
+
+       if (size == 0)
+               return -EINVAL;
 
        if (0 == *nbuffers)
                *nbuffers = 32;
        .vidioc_try_fmt_vid_cap   = vidioc_try_fmt_vid_cap,
        .vidioc_s_fmt_vid_cap     = vidioc_s_fmt_vid_cap,
        .vidioc_reqbufs       = vb2_ioctl_reqbufs,
+       .vidioc_create_bufs   = vb2_ioctl_create_bufs,
+       .vidioc_prepare_buf   = vb2_ioctl_prepare_buf,
        .vidioc_querybuf      = vb2_ioctl_querybuf,
        .vidioc_qbuf          = vb2_ioctl_qbuf,
        .vidioc_dqbuf         = vb2_ioctl_dqbuf,