[alsa-devel] ASOC v2 driver structure

[Jon Smirl]

On 1/28/08, Liam Girdwood <liam.girdwood at wolfsonmicro.com> wrote:
> On Sun, 2008-01-27 at 14:15 -0500, Jon Smirl wrote:
> > On 1/27/08, Jon Smirl <jonsmirl at gmail.com> wrote:
> > > I'm trying to write an asoc v2 driver for my powerpc based SOC
> > > (mpc5200) hardware. We have two audio devices on the board, a WM8580
> > > and a TAS5504.  How do you do this with asoc v2? The card is created
> > > in snd_soc_machine_create(); there seems to be an assumption of a
> > > single card per machine.
>
> This was the initial assumption in v1. To be honest we were only
> catering for single codec devices. In v2 we are allowing multiple cards
> - struct machine is being refactored atm to make this more obvious.

Another problem is how the drivers for the i2s/ac97 channels get
loaded. In the pxa270 the machine driver loads the i2s/ac97 driver and
it is hooked to the asoc bus. But in the powerpc world drivers for
these channels load via the device tree and they get hooked to the
of_platform_bus. Some of these assumptions in how machines are created
need to be changed to support these drivers on the of_platform_bus.


>
> > >
> > > Or are you supposed to mix the different devices into a single pcm
> > > driver? What would happen in pxa2xx-pcm.c if more than one of these
> > > were defined?
> >
> > I guess I'm supposed to have multiple platform drivers - one per
> > I2C/AC97/SSC channel?
> >
>
> You could do this or create two cards (machines). I've kept platform as
> the DMA + all the interfaces (as some devices have more than one
> interface in operation e.g. AC97 for HiFi and I2S/PCM for voice).
>
> Liam
>
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-- 
Jon Smirl
jonsmirl at gmail.com