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

[Shilimkar, Santosh]

On Sat, Mar 31, 2012 at 7:00 AM, Ming Lei <tom.leiming at gmail.com> wrote:
> 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.
>
So it's a PM disable kernel and you will recompile it.

> 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.
>
Since you need to recompile the kernel, you can very much tweak the
clocksource to use GPTIMER with sysl clock. Support for that is still
in place.

Regards
Santosh