At Wed, 25 Jul 2007 17:08:41 +0200,
I wrote:
>
> At Wed, 25 Jul 2007 09:37:34 -0500,
> Timur Tabi wrote:
> >
> > Takashi Iwai wrote:
> >
> > >> So can I do this?
> > >>
> > >> static const struct snd_pcm_hardware mpc86xx_pcm_hardware = {
> > >>
> > >> .rates = SNDRV_PCM_RATE_CONTINUOUS,
> > >> .rate_min = 1,
> > >> .rate_max = (unsigned int) -1,
> > >
> > > In theory, yes, but these rate_min and rate_max are nothing but
> > > confusing in practice. Your hardware won't support definitely such
> > > rates, but the application can't know. Set some reasonable values
> > > there.
> >
> > This is an ASOC driver. My understanding is that ASOC will take all
> > the values from the machine, PCM, I2S, and codec drivers and create
> > the subset that matches all drivers. That's the point I was trying
> > to make: my PCM driver does *not* decide what the capabilities of
> > the system are, because my DMA controller can handle all speeds. So
> > I don't want to put some arbitrary limits in the PCM driver, and
> > then perhaps one day it gets attached to a codec driver that can
> > handle 4000Hz, but ASOC won't allow it because I used
> > SNDRV_PCM_RATE_8000_192000 | SNDRV_PCM_RATES_5512 in my PCM driver.
> > ASOC would incorrectly believe that the PCM driver can't handle
> > 4000Hz.
>
> Then,
> rates = -1U,
> rate_min = 0,
> rate_max = -1U,
> are the correct values.
... of course, this assumes that codec and platform have the sane rate
setting. ASoC should do some sanity checks...
Takashi
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