2017-07-06 Hans Verkuil <hverkuil@xxxxxxxxx>: > 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. Sure, I'll add a comment explaining it. > > 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. You got it right. I should be doing that. Gustavo
