Hi Mark On Tue, Jul 4, 2023 at 12:03 PM Shengjiu Wang <shengjiu.wang@xxxxxxxxx> wrote: > > > On Tue, Jul 4, 2023 at 1:59 AM Mark Brown <broonie@xxxxxxxxxx> wrote: > >> On Mon, Jul 03, 2023 at 03:12:55PM +0200, Hans Verkuil wrote: >> >> > My main concern is that these cross-subsystem drivers are a pain to >> > maintain. So there have to be good reasons to do this. >> >> > Also it is kind of weird to have to use the V4L2 API in userspace to >> > deal with a specific audio conversion. Quite unexpected. >> >> > But in the end, that's a decision I can't make. >> >> > So I wait for that feedback. Note that if the decision is made that this >> > can use V4L2, then there is quite a lot more that needs to be done: >> > documentation, new compliance tests, etc. It's adding a new API, and >> that >> > comes with additional work... >> >> Absolutely, I agree with all of this - my impression was that the target >> here would be bypass of audio streams to/from a v4l2 device, without >> bouncing through an application layer. If it's purely for audio usage >> with no other tie to v4l2 then involving v4l2 does just seem like >> complication. >> > > This audio use case is using the v4l2 application layer. in the user space > I need to call below v4l2 ioctls to implement the feature: > VIDIOC_QUERYCAP > VIDIOC_TRY_FMT > VIDIOC_S_FMT > VIDIOC_REQBUFS > VIDIOC_QUERYBUF > VIDIOC_STREAMON > VIDIOC_QBUF > VIDIOC_DQBUF > VIDIOC_STREAMOFF > > why the driver was put in the ALSA, because previously we implemented > the ASRC M2P (memory to peripheral) in ALSA, so I think it is better to > add M2M driver in ALSA. The hardware IP is the same. The compatible > string is the same. > > > Could you please share more of your ideas about this patch? and could you please check further about this implementation. I tried to find a good interface in ALSA for this m2m request, but didn't find one, then I try the V4L2, find it is good this audio case. but it needs to extend the V4L2 API. I have no idea how to go on, could you please recommend? best regards wang shengjiu > >
