[alsa-devel] [PATCH 02/10] ASoc: mxs: add mxs-saif driver

Dong Aisheng dongas86 at gmail.com
Sun Jul 10 13:59:05 CEST 2011

2011/7/10 Mark Brown <broonie at opensource.wolfsonmicro.com>:
> On Sun, Jul 10, 2011 at 04:58:10PM +0800, Dong Aisheng wrote:
>> 2011/7/10 Mark Brown <broonie at opensource.wolfsonmicro.com>:
>> > On Sun, Jul 10, 2011 at 04:17:13PM +0800, Dong Aisheng wrote:
>> >> The problem is that the codec may use the MCLK supplied by SAIF as its
>> >> system clock for normal operations such as i2c r/w.
>> > That may be true for your particular system but it is not going to be
>> > true in general - most devices can handle having their MCLK removed.
>> Yes, if i cover that, that may make driver a little complicated.
>> Should i do that now or as the next work?
> It should simply be a case of adding handling of setting the sysclk to 0
> (this is how ASoC indicates clocks should be disabled).  The machine
> driver is then responsible for making sure it does the refcounting
> properly, and for your system where the clock is enabled all the time
> that's just a case of enabling on startup and disabling on remove.
Ok, i will take account of that.
Thanks for your suggestion.

>> Also i still do not have such type of codecs integrated on hand.
> That's fine, audio hardware is so flexible that it's unreasonable to
> expect that all possible systems have been tested.  So long as the code
> looks sensible it should be fine and if there are problems people can
> always come back and fix them.

>> > This is the same issue as the above one with repeated enables?  You
>> > should delegate the rate selection and ideally also the enable control
>> > to the machine driver, it can set something in its probe() function.
>> Not the same one. The repeated enables is a bug.(Will fix)
> Yes, but both are a result of the requirements of your CODEC?  Just
> trying to understand if the I2S controller needs this itself or if it's
> only for the CODEC.
Based on my understanding, only for codec.
I will double check it with IC man.

Dong Aisheng

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