Hi Mark On Fri, Jul 7, 2023 at 11:13 AM Shengjiu Wang <shengjiu.wang@xxxxxxxxx> wrote: > 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? > > Should I implement the asrc m2m driver as a separate v4l2 driver? And move it to the /driver/media folder ? In ALSA part, just need register the platform device. The bridge between ALSA and V4L2 framework can be the header file in /include/sound/ Does it sound better? Best regards Wang Shengjiu
