[PATCH] arch_timer: Move delay timer to drivers clocksource

[daniel.lezcano@linaro.org (Daniel Lezcano)]

On 01/17/2014 12:37 PM, Prashant Gaikwad wrote:
> On Friday 17 January 2014 03:45 PM, Daniel Lezcano wrote:
>> On 01/17/2014 11:11 AM, Prashant Gaikwad wrote:
>>> On Friday 17 January 2014 02:42 PM, Daniel Lezcano wrote:
>>>> On 01/17/2014 10:07 AM, Antti Miettinen wrote:
>>>>> Will Deacon <will.deacon@arm.com> writes:
>>>>>> Why can't you use the C3STOP feature so that the arch-timer isn't
>>>>>> used when
>>>>>> you go idle?
>>>>> That would mean falling back to broadcast timer, right? That's not
>>>>> necessarily on the local CPU so wakeups would often wake two CPUs.
>>>> You can prevent that if the hardware supports it with the
>>>> CLOCK_EVT_DYNIRQ flag on the broadcast timer.
>>> Instead of falling back on broadcast timer, is it possible to fall back
>>> on other per-CPU timer which is preserved across idle state?
>> Is it what you are looking for ?
>>
>> http://lwn.net/Articles/580568/
>>
>
> If I understand correctly these patches enables us to use per-CPU timers
> as broadcast timers. I do not want to use broadcast timer.

Why ?


> If I have 2 per-CPU timers T1 and T2, T1 is not preserved across idle
> state and T2 is preserved. And I want to use T1 as scheduler timer.
> Can I do following for idle state?
>
> Idle entry:
>      clockevents_shutdown(T1);
>      clockevents_set_mode(T2, ONESHOT);
>      clockevents_program_event(T2, next_event);
>
> Idle exit:
>      clockevents_shutdown(T2);
>      clockevents_set_mode(T1, ONESHOT);




>>>>> Does
>>>>> anyone have patches for using a CPU local timer as a fallback for
>>>>> C3STOP timers?
>>>>
>>
>


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