[alsa-devel] Ordering in soc_pcm_hw_params()

[jonsmirl at gmail.com]

On Tue, Aug 12, 2014 at 4:42 AM, Lars-Peter Clausen <lars at metafoo.de> wrote:
> On 08/11/2014 03:35 PM, jonsmirl at gmail.com wrote:
>>
>> soc_pcm_hw_params() sets the parameters in this order:
>> link, codec, cpu, platform
>>
>> This is tripping me up when switching between the 44100 and 48000
>> families.  If previous song was 44100 then the codec has sysclk set to
>> the 44100 family.
>>
>> Now I play a 48000 family song. codec gets new hardware params and
>> errors out because sysclk is still in the 44100 family.
>>
>> I have code in the cpu set_hw_params which will switch the sysclk, but
>> it never gets to run because the codec set_hw_params() has already
>> errored out.
>>
>> Shouldn't this order be:
>> platform, link, cpu, codec
>
>
> What I don't understand is why does the CPU DAI driver change the sysclk for
> the CODEC DAI driver? What I'd expect is that the machine driver sets the
> sysclk for both the CODEC and the CPU DAI. In this case everything should
> work fine.

The machine driver is simple-card. It is not smart enough to change
the sysclk between 22.5Mhz and 24.5Mhz depending on what music is
being played.


>
> - Lars
>



-- 
Jon Smirl
jonsmirl at gmail.com