On 07/03/17 20:16, Gustavo Padovan wrote: >>> @@ -1436,6 +1481,11 @@ int vb2_core_qbuf(struct vb2_queue *q, unsigned int index, void *pb) >>> if (pb) >>> call_void_bufop(q, fill_user_buffer, vb, pb); >>> >>> + vb->in_fence = fence; >>> + if (fence && !dma_fence_add_callback(fence, &vb->fence_cb, >>> + vb2_qbuf_fence_cb)) >>> + return 0; >> >> Maybe we should provide some error or debug log here or a WARN_ON(), if >> dma_fence_add_callback() fails instead of silently ignore any errors. > > This is not an error. If the if succeeds it mean we have installed a > callback for the fence. If not, it means the fence signaled already and > we don't can call __vb2_core_qbuf right away. I had the same question as Mauro. After looking at the dma_fence_add_callback code I see what you mean, but a comment would certainly be helpful. Also, should you set vb->in_fence to NULL if the fence signaled already? I'm not sure if you need to call 'dma_fence_put(vb->in_fence);' as well. You would know that better than I do. Regards, Hans
