Subject: [PATCH 2/2] ARM: omap: timers: reduce rating of gp_timer clocksource

From: [email-masked] (Tony Lindgren)
Date: Fri, 2 Dec 2016 10:31:40 -0800

* Grygorii Strashko <[email-masked]> [161202 10:02]:
> 
> 
> On 12/02/2016 10:47 AM, Tony Lindgren wrote:
> > * Grygorii Strashko <[email-masked]> [161129 08:43]:
> > > 
> > > 
> > > On 11/24/2016 12:19 AM, Keerthy wrote:
> > > > From: Grygorii Strashko <[email-masked]>
> > > > 
> > > > Now ARM Global timer (rating 300) will not be selected as clocksource,
> > > > because it's initialized after OMAP GP Timer (rating 300) and
> > > > Timekeeping core will not allow to replace clocksource with new one if
> > > > both of them have the same rating.
> > > > 
> > > > Reduce rating of OMAP GP Timer (300->290) when it's used as
> > > > clocksource device - this will allow to select ARM Global timer (300)
> > > > as clocksource when enabled.
> > > > 
> > > > Signed-off-by: Grygorii Strashko <[email-masked]>
> > > > Signed-off-by: Dave Gerlach <[email-masked]>
> > > > Signed-off-by: Keerthy <[email-masked]>
> > > 
> > > Unfortunately, this patch has dependency [1] and can't be used alone as
> > > it will cause ARM Global timer to be selected as clocksource
> > > always on am437x and this will kill cpuidle, because ARM Global timer
> > > is not in always_on domain.
> > > 
> > > The intention of enabling ARM Global timer is only for non-pm aware use
> > > cases for RT-kernel latency improvement - where deep cpuidle states are not
> > > enabled.
> > 
> > Yeah we need to fix up things to be able to change the clocksource
> > in addition to clockevent. However, currently only cpuidle_coupled
> > knows when the whole system is idle, so quite a bit of work is
> > needed to do that in a sane way.
> 
> Also sched_clock and timer_delay ;)

Yeah sched_clock would need something to save and restore it..
Not nice :)

> > What about the first patch in this series?
> > 
> 
> Fist one is ok. It was originally posted long time ago.

OK so can you please resend that one more time with proper
Fixes tag on it?

Regards,

Tony