Re: [PATCH v14 20/53] ASoC: Add SOC USB APIs for adding an USB backend

[Wesley Cheng <quic_wcheng@xxxxxxxxxxx>]

Hi Takashi,

On 2/10/2024 12:08 AM, Takashi Iwai wrote:
> On Fri, 09 Feb 2024 21:34:39 +0100,
> Wesley Cheng wrote:
> > Hi Takashi,
> >
> > On 2/9/2024 2:54 AM, Takashi Iwai wrote:
> > > On Fri, 09 Feb 2024 00:13:33 +0100,
> > > Wesley Cheng wrote:
> > > > Some platforms may have support for offloading USB audio devices to a
> > > > dedicated audio DSP.  Introduce a set of APIs that allow for management of
> > > > USB sound card and PCM devices enumerated by the USB SND class driver.
> > > > This allows for the ASoC components to be aware of what USB devices are
> > > > available for offloading.
> > > >
> > > > Signed-off-by: Wesley Cheng <quic_wcheng@xxxxxxxxxxx>
> > > (snip)
> > > > --- a/sound/soc/Makefile
> > > > +++ b/sound/soc/Makefile
> > > > @@ -1,5 +1,5 @@
> > > >    # SPDX-License-Identifier: GPL-2.0
> > > > -snd-soc-core-objs := soc-core.o soc-dapm.o soc-jack.o soc-utils.o soc-dai.o soc-component.o
> > > > +snd-soc-core-objs := soc-core.o soc-dapm.o soc-jack.o soc-usb.o soc-utils.o soc-dai.o soc-component.o
> > > >    snd-soc-core-objs += soc-pcm.o soc-devres.o soc-ops.o soc-link.o soc-card.o
> > > >    snd-soc-core-$(CONFIG_SND_SOC_COMPRESS) += soc-compress.o
> > >
> > > Do we really want to build this into ASoC core unconditionally?
> > > This is very specific to Qualcomm USB-offload stuff, so it's better to
> > > factor out.
> >
> > Ideally, the SOC USB part shouldn't be Qualcomm specific.  Since I
> > don't have access or insight into how other vendors are achieving the
> > same thing, I can only base the soc-usb layer to work with the
> > information that is required to get the audio stream up and running on
> > the QC platforms.  In its simplest form, its basically just a SW
> > entity that notifies ASoC components about changes occurring from USB
> > SND, and I think all vendors that have an ASoC based platform card
> > handling the offload will need this notification.
>
> Yes, but it's not necessarily built into the snd-soc-core module at
> all, but can be split to another module, right?  Otherwise all
> machines must load this code even if it doesn't use at all.
> If this were common among various chips, it'd be worth to be merged
> into the default common module.  But I don't think that's the case.

That's fair.  I'll make it a separate module and upload v15 tomorrow. 
Thanks for the explanation.

Thanks
Wesley Cheng