Re: [virtio-dev] [PATCH] snd: Add virtio sound device specification

[Jean-Philippe Brucker <jean-philippe@linaro.org>]

On Tue, Nov 12, 2019 at 02:20:44PM +0000, Liam Girdwood wrote:
> > Other virtio devices rely on the buffer length already provided by
> > virtio
> > for this. For example see the virtio-net control virtqueue
> > (virtio_net_ctrl*), which is extended with new commands from time to
> > time.
> > Most recently, the "receive-side scaling" feature introduces a large
> > structure as payload to virtio_net_ctrl.
> > 
> 
> Sorry, not following, what does this have to do with combining type and
> size into request_code ? Or are you saying the size is encoded
> elsewhere in the virtio transport data ?

Yes, the buffer size is encoded in the transport data.

[...]
> This would be a good improvement, it's less copying and would likely
> improve user experience, however the buffer ptr still suffers latency
> as it's queued (same for stream positions going the other way).

Right if the queuing overhead is still too large, then I don't think the
current virtqueues can be used.

Thanks,
Jean