[alsa-devel] [PATCH 4/7] ASoC: Automatically calculate clock ratio for WM8580

[Jassi Brar]

On Tue, Aug 17, 2010 at 6:46 PM, Mark Brown
<broonie at opensource.wolfsonmicro.com> wrote:
> On Tue, Aug 17, 2010 at 08:14:43AM +0900, Jassi Brar wrote:
>
>> I guess most quality conscious products can afford to attach a dedicated
>> OSC to a good CODEC. A CODEC already specifies the clocks it support
>> and usually comes with 'preferred' input clocks. So, just having a specified
>> rating accurate enough OSC can take care of quality. On the other hand
>> the clock sources on CPU side are not particularly accurate for audio-clock
>> generation. Or so have I seen so far.
>
> Right, this shouldn't be an issue with the change I proposed - the
> clocks are still rooted from the CODEC and its clock generation
> facilities would still be used, it's just that they get routed
> differently.
>
> The issue with using most CPU clocks isn't really the dedicated
> oscillator so much as the ability to generate non-integer divisions of
> whatever input clock is available.  If this can't be done then it can be
> hard to generate the full range of common audio frequencies.

Ok, now that I am faced with supporting latest SMDKs that use codecs
other than WM8580 (like wm8994), I think we'd better break the MACHINE
driver into SMDK specific (setup CPU master, CODEC slave and
root-clock sourced acc to option provided vai platform_data)
and CODEC specific part.
That will also help code reuse.

Any opinions, before I start working on it?

Thanks,
Jassi