On Fri, Mar 25, 2022 at 03:44:13PM +0900, Oh Eomji wrote:
> On Thu, Mar 24, 2022 at 09:33:40AM +0100, Greg Kroah-Hartman wrote:
> > On Thu, Mar 24, 2022 at 05:10:42PM +0900, Oh Eomji wrote:
> > > In mobile, a co-processor can be used with USB audio to improve power
> > > consumption. To support this type of hardware, hooks need to be added
> > > to the USB audio subsystem to be able to call into the hardware when
> > > needed.
> > >
> > > The main operation of the call-backs are:
> > > - Initialize the co-processor by transmitting data when initializing.
> > > - Change the co-processor setting value through the interface
> > > function.
> > > - Configure sampling rate
> > > - pcm open/close
> > > - other housekeeping
> > >
> > > Known issues:
> > > - This only supports one set of callback hooks, meaning that this only
> > > works if there is one type of USB controller in the system. This
> > > should be changed to be a per-host-controller interface instead of
> > > one global set of callbacks.
> > >
> > > Signed-off-by: JaeHun Jung <jh0801.jung@xxxxxxxxxxx>
> > > Signed-off-by: Oh Eomji <eomji.oh@xxxxxxxxxxx>
> > > ---
> > > sound/usb/card.c | 119 +++++++++++++++++++++++++++++++++++++++++++++++++++
> > > sound/usb/card.h | 20 +++++++++
> > > sound/usb/usbaudio.h | 45 +++++++++++++++++++
> > > 3 files changed, 184 insertions(+)
> > >
> > > diff --git a/sound/usb/card.c b/sound/usb/card.c
> > > index 3769622..bd59311 100644
> > > --- a/sound/usb/card.c
> > > +++ b/sound/usb/card.c
> > > @@ -117,6 +117,117 @@ MODULE_PARM_DESC(skip_validation, "Skip unit descriptor validation (default: no)
> > > static DEFINE_MUTEX(register_mutex);
> > > static struct snd_usb_audio *usb_chip[SNDRV_CARDS];
> > > static struct usb_driver usb_audio_driver;
> > > +static struct snd_usb_audio_vendor_ops *usb_vendor_ops;
> > > +
> > > +int snd_vendor_set_ops(struct snd_usb_audio_vendor_ops *ops)
> > > +{
> > > + if ((!ops->connect) ||
> > > + (!ops->disconnect) ||
> > > + (!ops->set_interface) ||
> > > + (!ops->set_rate) ||
> > > + (!ops->set_pcm_buf) ||
> > > + (!ops->set_pcm_intf) ||
> > > + (!ops->set_pcm_connection) ||
> > > + (!ops->set_pcm_binterval) ||
> > > + (!ops->usb_add_ctls))
> > > + return -EINVAL;
> > > +
> > > + usb_vendor_ops = ops;
> > > + return 0;
> > > +}
> > > +EXPORT_SYMBOL_GPL(snd_vendor_set_ops);
> > > +
> > > +struct snd_usb_audio_vendor_ops *snd_vendor_get_ops(void)
> > > +{
> > > + return usb_vendor_ops;
> > > +}
> >
> > This is the function you need to fix up, and add proper reference
> > counting to, in order to solve your "this breaks with multiple USB
> > controllers" problem. So this really should not be all that difficult
> > of a task. Why has it taken years to do so?
> >
> > thanks,
> >
> > greg k-h
> >
> Hi,
>
> Is that mean the scenario when two or more usb audio devices are
> connected through the hub?
I have no idea, it's your hardware and code to test, not mine :)
greg k-h
