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    SubjectRe: "cpufreq: fix serialization issues with freq change notifiers" breaks cpufreq too
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    On Monday, September 09, 2013 11:42:41 PM Guennadi Liakhovetski wrote:
    > Hi Rafael
    >
    > On Mon, 9 Sep 2013, Rafael J. Wysocki wrote:
    >
    > > Hi,
    > >
    > > On Monday, September 09, 2013 05:11:10 PM Guennadi Liakhovetski wrote:
    > > > Sorry guys, I'm trying my best to stop this patch from propagating to
    > > > stable and to get it fixed asap, so, the CC list might be a bit excessive.
    > > > Also trying to fix the originally spare cc list, which makes it impossible
    > > > for me to reply to the original thread, instead have to start a new one.
    > >
    > > I'm not sure what you're talking about. What exactly was wrong with the
    > > original CC list in particular?
    >
    > I think you advised once to cc cpufreq related mails to linux-pm too at
    > least.

    Yes, I did.

    > I haven't found this patch in my pm archive, have I missed it there?

    Quite frankly, I don't remember if it was there. ISTR having it it patchwork,
    which would mean that it was there, but well.

    > > > Commit
    > > >
    > > > commit dceff5ce18801dddc220d6238628619c93bc3cb6
    > > > Author: Viresh Kumar <viresh.kumar@linaro.org>
    > > > Date: Sun Sep 1 22:19:37 2013 +0530
    > > >
    > > > cpufreq: fix serialization issues with freq change notifiers
    > > >
    > > > breaks .transition_ongoing counting.
    > >
    > > Do you know how exactly it breaks that? If so, care to share that knowledge?
    >
    > No, I don't. I only know that in __cpufreq_driver_target() the check for
    >
    > if (policy->transition_ongoing) {
    > write_unlock_irqrestore(&cpufreq_driver_lock, flags);
    > return -EBUSY;
    > }
    >
    > is failing with this patch and cpufreq-cpu0.

    OK, we need to figure out that, then.

    > > > This leads to cpufreq-cpu0 not working any more. In particular switching the
    > > > governor from performance to powersave directly after boot doesn't result in
    > > > a frequency switch any more. Reverting this patch fixes the problem again.
    > >
    > > However, this is a regression fix, so I'd prefer to fix the problem on top of
    > > it instead of reverting this commit entirely.
    >
    > If I understood correctly, this patch fixed some warnings, that, however,
    > didn't disrupt functionality, is this right? Whereas the patch really
    > seems to break working set ups.

    It fixed warnings that indicated problems and those problems should rather be
    avoided.

    Thanks,
    Rafael



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