Re: [PATCH] cpufreq: Processor Clocking Control interface driver

From: Dominik Brodowski
Date: Tue Dec 15 2009 - 13:33:51 EST


Hey,

On Tue, Dec 15, 2009 at 06:08:08PM +0000, Chumbalkar, Nagananda wrote:
> Hi, I have addressed your concerns below:

Thanks!

> >If this is _really_ necessary... Doesn't the driver version
> >relate to some
> >Linux kernel version anyway?
> >
>
> If distros backport this driver to different kernel versions, it will be
> easy to keep track of which driver version is in the distro.

Well, IMVHO it's ugly, but if Linux ACPI and cpufreq folks are fine with
it, so be it.

> Yes, it works fine. Both "ondemand" and "conservative" sanitize the
> latency value, and set it to a default value which is good.

OK. Any way to fix the spec for the next revision, though?

> >> + if (target_freq <=
> >(ioread32(&pcch_hdr->minimum_frequency) * 1000)) {
> >> + target_freq =
> >ioread32(&pcch_hdr->minimum_frequency) * 1000;
> >> + dprintk("target: target_freq for cpu %d was
> >below limit, "
> >> + "converted it to %d\n", cpu, target_freq);
> >> + }
> >
> >why not do this in the _verify() step? Does pcch_hdr->minimum_frequency
> >even change "on the fly"?
>
> pcch_hdr->minimum_frequency does not change "on the fly". Also, there is no
> need for those IO accesses:

target_freq cannot be below policy->min or above policy->max. If it were,
the whole cpufreq subsystem is broken. So there's no need for these checks,
AFAICS.

Best,
Dominik
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