From:  Lennart Augustsson <lennart@augustsson.net>
	Date:  Tue, 05 Feb 2002 10:56:20 +0100

> Maybe checking for variable rate doesn't really work with some codecs?
> You could try testing for variable rate by setting some different rates in
> the codec and then read back what you get.

Did that (see last paragraph below) but presumably if the AC97_ENAB_VRA isn't 
sticking that might effect how it behaves.

> BTW, does your codec support variable rate?

According to http://developer.intel.com/design/chipsets/datashts/290687.htm

	The ICH2 AC '97 Controller features include:

	* Independent PCI functions for audio and modem.

	* Independent bus master logic for Mic input, PCM Audio input 
	  (2-channel stereo), PCM audio output (2, 4 or 6-channel stereo,
	  Modem input and Modem output.

	* 16 bit sample resolution

==>	* Multiple sample rates up to 48 KHz		<===

	* 16 GPIOs

	* Single modem line

	* Dual codec configuration with two SDIN pins


cheers
mark


> Mark Davies wrote:
> 
> > We are still unsuccessfully trying to get reasonable audio out of this chipset.
> > As far as we can see it should support variable sample rates, the
> > documentation claims to but even with the recently added support for variable
> > sample rates in the auich driver it still insists on sticking at 48000.
> >
> > Adding debugging to auich_attach() as below:
> >
> >                 [...]
> >         auich_read_codec(sc, AC97_REG_EXTENDED_ID, &ext_id);
> > printf("auich ext_id is %x\n", ext_id);
> >         if ((ext_id & (AC97_CODEC_DOES_VRA | AC97_CODEC_DOES_MICVRA)) != 0) {
> >                 auich_read_codec(sc, AC97_REG_EXTENDED_STATUS, &ext_status);
> > printf("auich ext_status is %x\n", ext_status);
> >                 if ((ext_id & AC97_CODEC_DOES_VRA) !=0)
> >                         ext_status |= AC97_ENAB_VRA;
> >                 if ((ext_id & AC97_CODEC_DOES_MICVRA) !=0)
> >                         ext_status |= AC97_ENAB_MICVRA;
> >                 auich_write_codec(sc, AC97_REG_EXTENDED_STATUS, ext_status);
> > printf("auich ext_status is %x\n", ext_status);
> >                 auich_read_codec(sc, AC97_REG_EXTENDED_STATUS, &ext_status);
> > printf("auich ext_status is %x\n", ext_status);
> >                 sc->sc_fixed_rate = 0;
> >         } else {
> >                 sc->sc_fixed_rate = 48000;
> >         }
> >                 [...]
> >
> > gives
> >
> > auich ext_id is 1
> > auich ext_status is 0
> > auich ext_status is 1
> > auich ext_status is 0
> >
> > The fact that AC97_ENAB_VRA isn't set in that last reading of ext_status looks
> > wrong to me.
> >
> > And then in auich_set_params() whatever sample rate gets set to the codec when
> > you read it back its always 48000.
> >
> > Can anybody suggest whats happening here and how to fix?
> >
> > cheers
> > mark
>