Re: [PATCH] clocksource: timer-atmel-pit: don't suspend/resume if unused

[Daniel Lezcano]

On 01/13/2015 11:47 AM, Thomas Gleixner wrote:
> On Mon, 12 Jan 2015, Daniel Lezcano wrote:
>
> > On 01/12/2015 03:04 PM, Nicolas Ferre wrote:
> > > Le 18/12/2014 15:05, Nicolas Ferre a Ãcrit :
> > > > From: Sylvain Rochet <sylvain.rochet@xxxxxxxxxxxx>
> > > >
> > > > Waiting for PIT to stop counting takes a long time:
> > > >     1/(Master clock/prescaler/PIVR)
> > > > = 1/(133 MHz     /16       /2^20)
> > > > = 126 ms
> > > >
> > > > Up to 126 ms if master clock is set to 133 MHz, skipping suspend/resume
> > > > of the unused PIT device reduce (suspend time + resume time) from ~140 ms
> > > > to ~17 ms.
> > > >
> > > > Signed-off-by: Sylvain Rochet <sylvain.rochet@xxxxxxxxxxxx>
> > > > [nicolas.ferre@xxxxxxxxx: move to newer clocksource driver]
> > > > Signed-off-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxx>
> > > > Cc: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
> > > > ---
> > > > Hi Sylvain,
> > > >
> > > > I re-worked (and "Acked") your patch so it can be applied on the newer
> > > > Mainline
> > > > kernels. Beware, I changed the "subject line" as well. The PIT driver
> > > > moved
> > > > recently (3.18).
> > > >
> > > > Daniel,
> > > > Can you take this patch in your tree?
> > >
> > > Hi Daniel,
> > >
> > > Anything prevents this patch from being merged (aka ping ;-))?
> >
> > [Cc'ed tglx].
> >
> > Hi Nico,
> >
> > thanks for the head up.
> >
> > Nothing prevents it but I am wondering if this change shouldn't be in the
> > generic framework (kernel/time/clocksource.c and kernel/time/clockevents.c),
> > so all drivers will benefit this change ?
>
> Indeed. There is no point in calling suspend/resume for unused
> clockevents. They should be stopped and disabled already.

Hi Nico,

are you planning to do the change in the generic framework ?

Thanks
  -- Daniel

> Now with clocksources this might be different. We have no explicit
> state for this, but its trivial to add one at least for those
> clocksources which have enable/disable callbacks. For the other ones
> not so much.





--
 <http://www.linaro.org/> Linaro.org â Open source software for ARM SoCs

Follow Linaro:  <http://www.facebook.com/pages/Linaro> Facebook |
<http://twitter.com/#!/linaroorg> Twitter |
<http://www.linaro.org/linaro-blog/> Blog

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/