Re: [PATCH 1/2] ARM: OMAP: dmtimer: fix sleeping function called from invalid context

Ramirez Luna, Omar
2011-12-13T01:49:07Z

On Mon, Dec 12, 2011 at 5:08 PM, Tony Lindgren <tony@atomide.com> wrote:
...
>> @@ -134,22 +134,13 @@ static void omap_dm_timer_reset(struct
>> omap_dm_timer *timer)
>>  int omap_dm_timer_prepare(struct omap_dm_timer *timer)
>>  {
>> ...
>> -       ret = omap_dm_timer_set_source(timer, OMAP_TIMER_SRC_32_KHZ);
>> ...
>>
>> All clocks requested are set to 32 KHz first, even with the current
>> approach, there exists another API to set a new source.
>>
>> To be honest I don't know why the clocks are set to 32 KHz first,
>> maybe the default call path for users should be:
>
> You need a functional clock for the timer registers to work
> I believe.

Sounds logic :)

>> omap_dm_timer_request
>
> Yes this would make sense. The omap_timer_list should be protected
> by a mutex. There should not be a need for spinlock there as
> omap_dm_timer_request should be only called during init. If that's
> not the case, the the driver using it is broken.

Ok, I made this patch thinking that 'request' could be called from any
context, but if that is not the case mutex should be fine.

>> omap_dm_timer_set_source (new explicit call)
>> omap_dm_timer_start
>
> Once the timer has been requested, there should not be a need
> for locking as there should be only one timer user using the
> timer specific registers.
>
>> And remove setting the source to 32 KHz by default in omap_dm_timer_request.
>
> That you may need to be able to do anything with the timer :)

Well the intention was for the user to call it explicitly so it didn't
look as a hard coded setting, but I can keep it.

IIUC, mutex should be held instead of spin lock, I can do the change
instead of this patch and see how it goes.

Thanks,

Omar
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