for (plane = 0; plane < vb->num_planes; ++plane) {
                unsigned long size = PAGE_ALIGN(vb->planes[plane].length);
 
-               mem_priv = call_ptr_memop(vb, alloc, q->alloc_ctx[plane],
+               mem_priv = call_ptr_memop(vb, alloc,
+                               q->alloc_ctx[plane] ? : &q->dev,
                                q->dma_attrs, size, dma_dir, q->gfp_flags);
                if (IS_ERR_OR_NULL(mem_priv))
                        goto free;
                vb->planes[plane].data_offset = 0;
 
                /* Acquire each plane's memory */
-               mem_priv = call_ptr_memop(vb, get_userptr, q->alloc_ctx[plane],
-                                     planes[plane].m.userptr,
-                                     planes[plane].length, dma_dir);
+               mem_priv = call_ptr_memop(vb, get_userptr,
+                               q->alloc_ctx[plane] ? : &q->dev,
+                               planes[plane].m.userptr,
+                               planes[plane].length, dma_dir);
                if (IS_ERR_OR_NULL(mem_priv)) {
                        dprintk(1, "failed acquiring userspace "
                                                "memory for plane %d\n", plane);
 
                /* Acquire each plane's memory */
                mem_priv = call_ptr_memop(vb, attach_dmabuf,
-                       q->alloc_ctx[plane], dbuf, planes[plane].length,
-                       dma_dir);
+                               q->alloc_ctx[plane] ? : &q->dev,
+                               dbuf, planes[plane].length, dma_dir);
                if (IS_ERR(mem_priv)) {
                        dprintk(1, "failed to attach dmabuf\n");
                        ret = PTR_ERR(mem_priv);
 
  *             caller. For example, for V4L2, it should match
  *             the V4L2_BUF_TYPE_* in include/uapi/linux/videodev2.h
  * @io_modes:  supported io methods (see vb2_io_modes enum)
+ * @dev:       device to use for the default allocation context if the driver
+ *             doesn't fill in the @alloc_ctx array.
  * @dma_attrs: DMA attributes to use for the DMA. May be NULL.
  * @fileio_read_once:          report EOF after reading the first buffer
  * @fileio_write_immediately:  queue buffer after each write() call
 struct vb2_queue {
        unsigned int                    type;
        unsigned int                    io_modes;
+       struct device                   *dev;
        const struct dma_attrs          *dma_attrs;
        unsigned                        fileio_read_once:1;
        unsigned                        fileio_write_immediately:1;