On Wed, 27 Jan 2010, Mark Brown wrote:
> On Wed, Jan 27, 2010 at 06:56:23PM +0100, Guennadi Liakhovetski wrote:
[snip]
> > + if (f_opclk) {
>
> ...
>
> > + if (16 * f_opclk < 3 * f_mclk || 4 * f_opclk >= 13 * f_mclk)
> > + return -EINVAL;
> > +
> > + if (4 * f_opclk < 3 * f_mclk)
> > + /* Have to use OPCLKDIV */
> > + opclk_div = (3 * f_mclk / 4 + f_opclk - 1) / f_opclk;
> > + else
> > + opclk_div = 1;
>
> I'm fairly sure this and the similar logic for SYSCLK can be squashed
> together with some suitable local variables. Might be more legible
> since this requires some staring at. I didn't actually go so far as to
> work out what the relevant code is, though.
Well, not really. In one case f_PLLOUT can be derived directly, because
OPCLKDIV covers the whole its value range 1-4, whereas MCLKDIV takes
values 1, 3/2, 2, 3, 4, 6, 8, 12, so, you have to apply an iterative
process to select the best match. I've just sent a patch, that improves
these calculations. It should be the last patch for my SIU / wm8978 /
migor support so far.
Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
_______________________________________________
Alsa-devel mailing list
Alsa-devel@xxxxxxxxxxxxxxxx
http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
