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

[Shilimkar, Santosh]

On Fri, Mar 30, 2012 at 2:42 PM, Hiremath, Vaibhav <hvaibhav at ti.com> wrote:
> On Fri, Mar 30, 2012 at 14:08:20, Shilimkar, Santosh wrote:
>> On Friday 30 March 2012 02:02 PM, Hiremath, Vaibhav wrote:
>> > On Fri, Mar 30, 2012 at 13:11:35, Shilimkar, Santosh wrote:

[....]

>> >
>> > With this patch, will you be able to choose gptimer as a clocksource
>> > using bootparameter (or sysfs) for given kernel uImage?
>> >
>> Why do you want that ? Look at changelog. The gptimer based clocksource
>> is useless for OMAP and for AM devices synctimer is not available.
>>
>>
>> > The answer is simply NO...as the registration of gptimer is based on
>> > failure from omap_init_clocksource_32k(). And this is nothing different
>> > than my original patch, my patch exactly does same thing.
>> >
>> I ight have missed your original patch. If that patch is similar then
>> no problems.
>>
>> > The requirement after 'ming Lie' response on my patch was, there will be
>> > usecases where we might need to use gptimer for clocksource and with
>> > the patch it is not possible, since you will only register
>> > 32k_counter here.
>> >
>> I think Ming Lie might have expected that gptimer clocksource might
>> be better which is not the case.
>>
>> > So in order to allow user to choose between 32K and gptimer, you must
>> > register both and make 32k as a default thing.
>> >
>> As described in the commit log, its not needed at all. Let's not add
>> a feature which is just useless because the gptimer based clock
>> source has no advantage against the syntimer.
>>
>
> I completely agree with you, and that is my understanding too.
>
Thanks !!

> 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.

> I am quite not sure, whether will there be any practical usecase where you
> change the kernel clocksource for high resolution dynamically through sysfs
> or something. May be not....but still it is possible.
>
Even if there is a usecase, there no option with full PM.

>
> In that case my original patch still holds good here. I would still request
> you to review the same and give your acked-by  or tested-by.
>
I just looked at that.
It looks fine to me. Can you repost that patch addressing Kevin and
Tony's comments.
Also update the change log as describe in the patch i posted.

Once that done, will ack it.

Regards
Santosh