[PATCH] clocksource: timer-atmel-pit: don't suspend/resume if unused

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

On 01/15/2015 12:52 PM, Alexandre Belloni wrote:
> Hi,
>
> I'll do it but only if you review my other series :)

deal ! ;)

   -- Daniel


>
> On 15/01/2015 at 12:41:27 +0100, Daniel Lezcano wrote :
>> On 01/13/2015 11:47 AM, Thomas Gleixner wrote:
>>> On Mon, 12 Jan 2015, Daniel Lezcano wrote:
>>>
>>>> On 01/12/2015 03:04 PM, Nicolas Ferre wrote:
>>>>> Le 18/12/2014 15:05, Nicolas Ferre a ?crit :
>>>>>> From: Sylvain Rochet <sylvain.rochet@finsecur.com>
>>>>>>
>>>>>> Waiting for PIT to stop counting takes a long time:
>>>>>>     1/(Master clock/prescaler/PIVR)
>>>>>> = 1/(133 MHz     /16       /2^20)
>>>>>> = 126 ms
>>>>>>
>>>>>> Up to 126 ms if master clock is set to 133 MHz, skipping suspend/resume
>>>>>> of the unused PIT device reduce (suspend time + resume time) from ~140 ms
>>>>>> to ~17 ms.
>>>>>>
>>>>>> Signed-off-by: Sylvain Rochet <sylvain.rochet@finsecur.com>
>>>>>> [nicolas.ferre at atmel.com: move to newer clocksource driver]
>>>>>> Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
>>>>>> Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
>>>>>> ---
>>>>>> Hi Sylvain,
>>>>>>
>>>>>> I re-worked (and "Acked") your patch so it can be applied on the newer
>>>>>> Mainline
>>>>>> kernels. Beware, I changed the "subject line" as well. The PIT driver
>>>>>> moved
>>>>>> recently (3.18).
>>>>>>
>>>>>> Daniel,
>>>>>> Can you take this patch in your tree?
>>>>>
>>>>> Hi Daniel,
>>>>>
>>>>> Anything prevents this patch from being merged (aka ping ;-))?
>>>>
>>>> [Cc'ed tglx].
>>>>
>>>> Hi Nico,
>>>>
>>>> thanks for the head up.
>>>>
>>>> Nothing prevents it but I am wondering if this change shouldn't be in the
>>>> generic framework (kernel/time/clocksource.c and kernel/time/clockevents.c),
>>>> so all drivers will benefit this change ?
>>>
>>> Indeed. There is no point in calling suspend/resume for unused
>>> clockevents. They should be stopped and disabled already.
>>
>> Hi Nico,
>>
>> are you planning to do the change in the generic framework ?
>>
>> Thanks
>>    -- Daniel
>>
>>> Now with clocksources this might be different. We have no explicit
>>> state for this, but its trivial to add one at least for those
>>> clocksources which have enable/disable callbacks. For the other ones
>>> not so much.
>>
>>
>>
>>
>>
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>


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