Re: [PATCH] clocksource: sh_tmu: Set cpu_possible_mask to fix SMP broadcast

Laurent Pinchart
2014-12-16T11:25:15Z

Hi Magnus,

On Tuesday 16 December 2014 13:20:56 Laurent Pinchart wrote:
> On Tuesday 16 December 2014 12:14:40 Daniel Lezcano wrote:
> > On 12/16/2014 10:48 AM, Magnus Damm wrote:
> > > From: Magnus Damm <damm+renesas@opensource.se>
> > >
> > > Update the TMU driver to use cpu_possible_mask as cpumask to make
> > > r8a7779 SMP work as expected with or without the ARM TWD timer.
> > >
> > > Signed-off-by: Magnus Damm <damm+renesas@opensource.se>
> >
> > Applied as a 3.18 fix.
>
> You're a bit too fast, I haven't had time to review the patch yet.
>
> > ps: May I suggest to use the CLOCK_EVT_FEAT_DYNIRQ flag for this driver ?
> >
> > > ---
> > >
> > > drivers/clocksource/sh_tmu.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > --- 0001/drivers/clocksource/sh_tmu.c
> > > +++ work/drivers/clocksource/sh_tmu.c 2014-12-16 17:49:49.000000000
> > > +0900
> > > @@ -428,7 +428,7 @@ static void sh_tmu_register_clockevent(s
> > >
> > > ced->features = CLOCK_EVT_FEAT_PERIODIC;
> > > ced->features |= CLOCK_EVT_FEAT_ONESHOT;
> > > ced->rating = 200;
> > >
> > > - ced->cpumask = cpumask_of(0);
> > > + ced->cpumask = cpu_possible_mask;
>
> Magnus, how thoroughly have you tested this ? The TMU is indeed usable by
> all CPUs, so setting the CPU mask to cpu_possible_mask makes sense, but
> last time I've tried that it broke the broadcast timer due to the
> heuristics used by the clock events core code.
>
> Could you please confirm that you've tested both CONFIG_PREEMPT_NONE and
> CONFIG_PREEMPT with and without the ARM TWD times, and that you've booted to
> userspace and tested timer broadcast on all CPUs ?

I forgot to mention that this should be tested on R8A7740 with TMU only and
both TMU and CMT, and on r8A7779 with TMU only both TMU and TWD.

Without getting test results I'm afraid I must NACK the patch.

> > > ced->set_next_event = sh_tmu_clock_event_next;
> > > ced->set_mode = sh_tmu_clock_event_mode;
> > > ced->suspend = sh_tmu_clock_event_suspend;

--
Regards,

Laurent Pinchart