Re: [PATCH v3] clocksource: arm_global_timer: fix suspend resume

[Grygorii Strashko]

On 11/30/2015 02:29 AM, santosh.shilimkar@xxxxxxxxxx wrote:
> On 11/27/15 11:47 AM, Grygorii Strashko wrote:
> > Now the System stall is observed on TI AM437x based board
> > (am437x-gp-evm) during resuming from System suspend when ARM Global
> > timer is selected as clocksource device (CPUIdle not enabled) - SysRq
> > are working,
> > but nothing else.
> >
> > The reason of stall is that ARM Global timer loses its contexts during
> > System suspend:
> >     GT_CONTROL.TIMER_ENABLE = 0 (unbanked)
> >     GT_COUNTERx = 0
> >
> > Hence, update ARM Global timer driver to reflect above behaviour
> > - re-enable ARM Global timer on resume GT_CONTROL.TIMER_ENABLE = 1.
> >
> > CC: Arnd Bergmann <arnd@xxxxxxxx>
> > Cc: John Stultz <john.stultz@xxxxxxxxxx>
> > Cc: Felipe Balbi <balbi@xxxxxx>
> > Cc: Tony Lindgren <tony@xxxxxxxxxxx>
> > Cc: Santosh Shilimkar <ssantosh@xxxxxxxxxx>
> > Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
> > Signed-off-by: Grygorii Strashko <grygorii.strashko@xxxxxx>
> > ---
> > Changes in v3:
> >   - dropped all DT specific code
> > Changes in v2:
> >   - suspend/resume simplified: nothing is stored any more and
> >     ARM GT just re-enabled
> > Link on v2:
> >   https://lkml.org/lkml/2015/11/20/355
> > Link on v1:
> >   https://lkml.org/lkml/2015/11/13/456
> Looks reasonable to me.
> >   drivers/clocksource/arm_global_timer.c | 7 +++++++
> >   1 file changed, 7 insertions(+)
> >
> > diff --git a/drivers/clocksource/arm_global_timer.c
> > b/drivers/clocksource/arm_global_timer.c
> > index a2cb6fa..10d1417 100644
> > --- a/drivers/clocksource/arm_global_timer.c
> > +++ b/drivers/clocksource/arm_global_timer.c
> > @@ -195,12 +195,19 @@ static cycle_t gt_clocksource_read(struct
> > clocksource *cs)
> >       return gt_counter_read();
> >   }
> >
> > +static void gt_resume(struct clocksource *cs)
> > +{
> > +    /* re-enable timer on resume */
> > +    writel(GT_CONTROL_TIMER_ENABLE, gt_base + GT_CONTROL);
>
> Check if its disabled before enabling it.
> Other than that,
> Reviewed-by: Santosh Shilimkar <ssantosh@xxxxxxxxxx>

Sure, I'll update.

Thanks.
--
regards,
-grygorii
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