[alsa-devel] [PATCH] ad1848 and cs4231 busy loop replacement

[Krzysztof Helt]

On Sun, 09 Sep 2007 23:19:56 +0200
Rene Herman <rene.herman at gmail.com> wrote:

> On 09/09/2007 11:09 PM, Rene Herman wrote:
> 
> > Given that the only difference is that I wait less, yours would've 
> > worked as well -- thanks for looking into this! And could you viceversa 
> > test this on AD1848 and perhaps resubmit if you agree?
> 
> Oh, and I forgot to say (sigh) that I use a mdelay() and not an msleep() in 
> the ad1848 one due to the 1 ms being short enough and didn't keep the 
> snd_printd() because if one, then all please...
> 

I tested CS4231 on 450MHz sparc with 1000Hz kernel (I don't have PC card yet).
The waiting loop was changed as in my second patch (the 10ms blocks 
to schedule_timeout()). I played 48kHz wav (alsa "Front_Center.wav").

The waiting loop was passed 340 times after mce was down with msleep(1).
The delay between snd_printd "2 jiffies" and "8 jiffies" was 3 jiffies.

The waiting loop was passed 34 times after mce was down with msleep(2).
The delay between snd_printd "2 jiffies" and "8 jiffies" was 3 jiffies too.

It took about ten times less loop passes if the driver waits 2ms.
The 2ms seems like the optimal value for the CS4231.

Regards,
Krzysztof