}
EXPORT_SYMBOL_GPL(vb2_prepare_buf);
+/**
+ * vb2_start_streaming() - Attempt to start streaming.
+ * @q: videobuf2 queue
+ *
+ * If there are not enough buffers, then retry_start_streaming is set to
+ * 1 and 0 is returned. The next time a buffer is queued and
+ * retry_start_streaming is 1, this function will be called again to
+ * retry starting the DMA engine.
+ */
+static int vb2_start_streaming(struct vb2_queue *q)
+{
+ int ret;
+
+ /* Tell the driver to start streaming */
+ ret = call_qop(q, start_streaming, q, atomic_read(&q->queued_count));
+
+ /*
+ * If there are not enough buffers queued to start streaming, then
+ * the start_streaming operation will return -ENOBUFS and you have to
+ * retry when the next buffer is queued.
+ */
+ if (ret == -ENOBUFS) {
+ dprintk(1, "qbuf: not enough buffers, retry when more buffers are queued.\n");
+ q->retry_start_streaming = 1;
+ return 0;
+ }
+ if (ret)
+ dprintk(1, "qbuf: driver refused to start streaming\n");
+ else
+ q->retry_start_streaming = 0;
+ return ret;
+}
+
static int vb2_internal_qbuf(struct vb2_queue *q, struct v4l2_buffer *b)
{
int ret = vb2_queue_or_prepare_buf(q, b, "qbuf");
/* Fill buffer information for the userspace */
__fill_v4l2_buffer(vb, b);
+ if (q->retry_start_streaming) {
+ ret = vb2_start_streaming(q);
+ if (ret)
+ return ret;
+ }
+
dprintk(1, "%s() of buffer %d succeeded\n", __func__, vb->v4l2_buf.index);
return 0;
}
return -EINVAL;
}
- wait_event(q->done_wq, !atomic_read(&q->queued_count));
+ if (!q->retry_start_streaming)
+ wait_event(q->done_wq, !atomic_read(&q->queued_count));
return 0;
}
EXPORT_SYMBOL_GPL(vb2_wait_for_all_buffers);
{
unsigned int i;
+ if (q->retry_start_streaming) {
+ q->retry_start_streaming = 0;
+ q->streaming = 0;
+ }
+
/*
* Tell driver to stop all transactions and release all queued
* buffers.
list_for_each_entry(vb, &q->queued_list, queued_entry)
__enqueue_in_driver(vb);
- /*
- * Let driver notice that streaming state has been enabled.
- */
- ret = call_qop(q, start_streaming, q, atomic_read(&q->queued_count));
+ /* Tell driver to start streaming. */
+ ret = vb2_start_streaming(q);
if (ret) {
- dprintk(1, "streamon: driver refused to start streaming\n");
__vb2_queue_cancel(q);
return ret;
}
goto err_reqbufs;
fileio->bufs[i].queued = 1;
}
-
- /*
- * Start streaming.
- */
- ret = vb2_streamon(q, q->type);
- if (ret)
- goto err_reqbufs;
}
+ /*
+ * Start streaming.
+ */
+ ret = vb2_streamon(q, q->type);
+ if (ret)
+ goto err_reqbufs;
+
q->fileio = fileio;
return ret;