Messages in this thread | | | Date | Wed, 09 Oct 2013 16:35:35 -0700 | From | John Stultz <> | Subject | Re: [PATCH v2] clocksource: fix misleading comment for __clocksource_updatefreq_scale() |
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On 09/17/2013 07:57 PM, Xie XiuQi wrote: > Functions clocksource_updatefreq_hz() and clocksource_updatefreq_khz() > mentioned in the comment of __clocksource_updatefreq_scale() do not exist. > > As Thomas Gleixner's suggestion, I renamed the functions and the few call > sites because the underscores are completely meaningless.
First of all, sorry for taking so long to reply here.
So I think the __ tries to imply that those are semi-internal functions that aren't to be causally used w/o understanding the internal details.
> Signed-off-by: Xie XiuQi <xiexiuqi@huawei.com> > Cc: Thomas Gleixner <tglx@linutronix.de> > --- > drivers/clocksource/cadence_ttc_timer.c | 2 +- > drivers/clocksource/em_sti.c | 2 +- > drivers/clocksource/sh_cmt.c | 2 +- > drivers/clocksource/sh_tmu.c | 2 +- > include/linux/clocksource.h | 4 ++-- > 5 files changed, 6 insertions(+), 6 deletions(-) > > diff --git a/drivers/clocksource/cadence_ttc_timer.c b/drivers/clocksource/cadence_ttc_timer.c > index 4cbe28c..05f00e7 100644 > --- a/drivers/clocksource/cadence_ttc_timer.c > +++ b/drivers/clocksource/cadence_ttc_timer.c > @@ -226,7 +226,7 @@ static int ttc_rate_change_clocksource_cb(struct notifier_block *nb, > * Do whatever is necessary to maintain a proper time base > * > * I cannot find a way to adjust the currently used clocksource > - * to the new frequency. __clocksource_updatefreq_hz() sounds > + * to the new frequency. clocksource_updatefreq_hz() sounds > * good, but does not work. Not sure what's that missing. > *
So I know you didn't write the comment, but my issue with this comment is that there isn't a way to adjust the currently used clocksource frequency, because that is totally unsupported. The __clocksource_updatefreq_hz() method is really only there for clocksources that are currently not in-use and are disabled. Specifically for clocksources that may come out of resume at a different frequency, like the sh_ ones. Hacks like what the cadence_ttc driver is trying to do result in very poor timekeeping.
So I'm sort of on the fence about this patch.
Thomas: Any other thoughts?
thanks -john
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