On Thu, Aug 12, 2021 at 07:58:22PM +0800, Lecopzer Chen wrote:

Hi Greg

Reason:

We found without this, Poll() infinitely wait because OUTPUT queue will never signaled after last CAPTURE queue is de-queued. And some buffer can't be popped as expected.

commit id: 566463afdbc43c7744c5a1b89250fc808df03833 subject: "media: v4l2-mem2mem: always consider OUTPUT queue during poll"

This should be applied to 4.4+ without conflict after (f1a81afc98e315f4bf600d28f8a19a5655f7cfe0 "[media] m2m: fix bad unlock balance")

Applied to 5.4.y, but if you want it to go older, we need backported versions as it did not apply cleanly.

thanks,

greg k-h