[RFC v2 12/18] ARM: OMAP2+: timer: Add suspend-resume callbacks for clockevent device

[Santosh Shilimkar]

On Friday 18 January 2013 12:15 AM, Jon Hunter wrote:
>
> On 01/10/2013 10:37 PM, Bedia, Vaibhav wrote:
>> On Tue, Jan 08, 2013 at 20:45:10, Shilimkar, Santosh wrote:
>>> On Monday 31 December 2012 06:37 PM, 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 at ti.com>
>>>> Cc: Santosh Shilimkar <santosh.shilimkar at ti.com>
>>>> Cc: Benoit Cousson <b-cousson at ti.com>
>>>> Cc: Paul Walmsley <paul at pwsan.com>
>>>> Cc: Kevin Hilman <khilman at deeprootsystems.com>
>>>> Cc: Vaibhav Hiremath <hvaibhav at ti.com>
>>>> Cc: Jon Hunter <jon-hunter at ti.com>
>>>> ---
>>>> 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);
>>>> +	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);
>>>> +}
>>>> +
>>> Am still bit uncomfortable with direct hwmod usage in the suspend/resmue
>>> hooks.
>>>
>>> Jon, Any alternatives you can think of ?
>>>
>>
>> Jon,
>>
>> Any suggestions here?
>
> Sorry completed this missed this!
>
> Unfortunately, I don't have any good suggestions here. However, I am
> wondering if the suspend/resume handlers can just be calls to
> omap_hwmod_idle/enable and we can remove these __omap_dm_timer_xxxx
> calls (I don't think they are needed). Furthermore, my understanding is
> this is only needed for AM335x (per the changelog), and so we should not
> add suspend/resume handlers for all OMAP2+ based devices.
>
I agree with the direction.

Regards,
Santosh