Re: [RFC PATCH 03/14] ASoC: qcom: Add USB backend ASoC driver for Q6

Takashi Iwai
2022-12-27T14:02:38Z

On Tue, 27 Dec 2022 14:45:13 +0100,
Greg KH wrote:
>
> On Tue, Dec 27, 2022 at 01:04:55PM +0000, Mark Brown wrote:
> > On Sat, Dec 24, 2022 at 10:02:59AM +0100, Greg KH wrote:
> > > On Fri, Dec 23, 2022 at 03:31:49PM -0800, Wesley Cheng wrote:
> >
> > > > + * struct q6usb_offload
> > > > + * @dev - dev handle to usb be
> >
> > > "be"? What is that?
> >
> > Back end. This is a concept in DPCM which should be reasonably
> > discoverable to people working on the audio portions of this code.
>
> Ok, then how is the reference counting logic handled here? USB devices
> can be removed from the system at any point in time...

The whole picture is fairly complex, and this patch is a part
belonging to the ASoC machine driver -- that is, it's bound to the
Qualcomm host, and there can be only one on a system.

OTOH, USB audio devices are still managed by the existing USB audio
driver as is, and they can be multiple and any devices. The basic
idea here is a hijack of the USB data processing in USB audio driver
with the offloading mechanism by this ASoC driver (only if the
condition met).

thanks,

Takashi