Here's another videobuf2 question...I've been trying to track down some
weird behavior, the roots of which were in the fact that start_streaming()
gets called even though no buffers have been queued. This behavior is
quite explicit in the code:
/*
* Let driver notice that streaming state has been enabled.
*/
ret = call_qop(q, start_streaming, q);
if (ret) {
dprintk(1, "streamon: driver refused to start streaming\n");
return ret;
}
q->streaming = 1;
/*
* If any buffers were queued before streamon,
* we can now pass them to driver for processing.
*/
list_for_each_entry(vb, &q->queued_list, queued_entry)
__enqueue_in_driver(vb);
Pretty much every v4l2 capture application I've ever encountered passes all
of its buffers to VIDIOC_QBUF before starting streaming for a reason - it
makes little sense to start if there's nothing to stream to. It's really
tempting to reorder that code, but... it seems you must have done things
this way for a reason. Why did you need to reorder the operations in this
way?
(Yes, my driver's current tendency to go oops when start_streaming() gets
called with no buffers is a bug, I'll fix it regardless).
Thanks,
jon
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