[PATCH 1/3] ARM: OMAP2+: 32k-counter: Use hwmod lookup to check presence of 32k timer

Ming Lei tom.leiming at gmail.com
Fri Mar 30 21:30:31 EDT 2012


On Fri, Mar 30, 2012 at 5:20 PM, Shilimkar, Santosh <santosh.shilimkar at ti.com>
>
>> After Ming Lie's comment, the point that I came to my mind was,
>> certainly there will be resolution difference between these two clocksources,
>> if  gptimer2 is sourced from sys_ck (26Mhz).
>>
> GPTIMER2 with sysclock is not an option. GPTIMER is not in wakeup domain
> and when sysclock is cut, it stops.

If neither CONFIG_PM or CONFIG_CPUIDLE is set, GPTIMER2 with sysclock
should be an option.

As I commented before, high resolution timer is very useful for trace, debug or
high frequency perf sample. Suppose you want to trace the running time of
one function,  32K counter can only give you a resolution of ~35us, which is
too coarse to work well.


Thanks,
-- 
Ming Lei



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