Hi Jon,
On Fri, Jan 18, 2013 at 00:10:40, Hunter, Jon wrote:
>
> On 12/31/2012 07:07 AM, Vaibhav Bedia wrote:
> > The current OMAP timer code registers two timers -
> > one as clocksource and one as clockevent.
> > AM33XX has only one usable timer in the WKUP domain
> > so one of the timers needs suspend-resume support
> > to restore the configuration to pre-suspend state.
> >
> > commit adc78e6 (timekeeping: Add suspend and resume
> > of clock event devices) introduced .suspend and .resume
> > callbacks for clock event devices. Leverages these
> > callbacks to have AM33XX clockevent timer which is
> > in not in WKUP domain to behave properly across system
> > suspend.
> >
> > Signed-off-by: Vaibhav Bedia <vaibhav.bedia@xxxxxx>
> > Cc: Santosh Shilimkar <santosh.shilimkar@xxxxxx>
> > Cc: Benoit Cousson <b-cousson@xxxxxx>
> > Cc: Paul Walmsley <paul@xxxxxxxxx>
> > Cc: Kevin Hilman <khilman@xxxxxxxxxxxxxxxxxxx>
> > Cc: Vaibhav Hiremath <hvaibhav@xxxxxx>
> > Cc: Jon Hunter <jon-hunter@xxxxxx>
> > ---
> > v1->v2:
> > Get rid of harcoded timer id.
> > Note: since a platform device is not created for these timer
> > instances and because there's very minimal change needed for
> > restarting the timer a full blown context save and restore
> > has been skipped.
> >
> > arch/arm/mach-omap2/timer.c | 33 +++++++++++++++++++++++++++++++++
> > 1 files changed, 33 insertions(+), 0 deletions(-)
> >
> > diff --git a/arch/arm/mach-omap2/timer.c b/arch/arm/mach-omap2/timer.c
> > index 691aa67..38f9cbc 100644
> > --- a/arch/arm/mach-omap2/timer.c
> > +++ b/arch/arm/mach-omap2/timer.c
> > @@ -128,6 +128,36 @@ static void omap2_gp_timer_set_mode(enum clock_event_mode mode,
> > }
> > }
> >
> > +static void omap_clkevt_suspend(struct clock_event_device *unused)
> > +{
> > + char name[10];
> > + struct omap_hwmod *oh;
> > +
> > + sprintf(name, "timer%d", clkev.id);
> > + oh = omap_hwmod_lookup(name);
> > + if (!oh)
> > + return;
> > +
> > + __omap_dm_timer_stop(&clkev, 1, clkev.rate);
>
> I am not sure you need to call __omap_dm_timer_stop() here. This should
> have already been called as timekeeping_suspend() will call
> omap2_gp_timer_set_mode() to shutdown the timer.
You are right, i can drop the call to __omap_dm_timer_stop().
>
> > + omap_hwmod_idle(oh);
> > +}
> > +
> > +static void omap_clkevt_resume(struct clock_event_device *unused)
> > +{
> > + char name[10];
> > + struct omap_hwmod *oh;
> > +
> > + sprintf(name, "timer%d", clkev.id);
> > + oh = omap_hwmod_lookup(name);
> > + if (!oh)
> > + return;
> > +
> > + omap_hwmod_enable(oh);
> > + __omap_dm_timer_load_start(&clkev,
> > + OMAP_TIMER_CTRL_ST | OMAP_TIMER_CTRL_AR, 0, 1);
> > + __omap_dm_timer_int_enable(&clkev, OMAP_TIMER_INT_OVERFLOW);
>
> Similarly here, I am not sure these __omap_dm_timer_xxxx calls are needed.
I went through the code again. __omap_dm_timer_load_start() is invoked
from omap2_gp_timer_set_mode() with the auto-reload flag when setting the
mode to CLOCK_EVT_MODE_PERIODIC and without the auto-reload flag in
omap2_gp_timer_set_next_event(). So looks like this call can be dropped.
But I do need the call to __omap_dm_timer_int_enable() to re-enable the
interrupts from the timer.
>
> > +}
> > +
> > static struct clock_event_device clockevent_gpt = {
> > .name = "gp_timer",
> > .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
> > @@ -135,6 +165,8 @@ static struct clock_event_device clockevent_gpt = {
> > .rating = 300,
> > .set_next_event = omap2_gp_timer_set_next_event,
> > .set_mode = omap2_gp_timer_set_mode,
> > + .suspend = omap_clkevt_suspend,
> > + .resume = omap_clkevt_resume,
>
> AFAIK, this is only applicable for AM335x devices and so should not be
> added for all.
>
Agreed. Will address this in the next version.
> > };
> >
> > static struct property device_disabled = {
> > @@ -323,6 +355,7 @@ static void __init omap2_gp_clockevent_init(int gptimer_id,
> > int res;
> >
> > clkev.errata = omap_dm_timer_get_errata();
> > + clkev.id = gptimer_id;
>
> We should not use gptimer_id anymore. This will go away once the
> migration to dev-tree is completed. You may be better off storing the
> oh_name in the clock_event_device name field and passing to the
> suspend/resume handlers.
>
Currently the name field in clock_event_device is set to "gp_timer". Should I set
the name in omap2_gp_clockevent_init() based on the gptimer_id?
Regards,
Vaibhav
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