lkml.org 
[lkml]   [2016]   [Dec]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 2/2] ARM: omap: timers: reduce rating of gp_timer clocksource
From
Date


On 12/02/2016 10:47 AM, Tony Lindgren wrote:
> * Grygorii Strashko <grygorii.strashko@ti.com> [161129 08:43]:
>>
>>
>> On 11/24/2016 12:19 AM, Keerthy wrote:
>>> From: Grygorii Strashko <grygorii.strashko@ti.com>
>>>
>>> Now ARM Global timer (rating 300) will not be selected as clocksource,
>>> because it's initialized after OMAP GP Timer (rating 300) and
>>> Timekeeping core will not allow to replace clocksource with new one if
>>> both of them have the same rating.
>>>
>>> Reduce rating of OMAP GP Timer (300->290) when it's used as
>>> clocksource device - this will allow to select ARM Global timer (300)
>>> as clocksource when enabled.
>>>
>>> Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
>>> Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
>>> Signed-off-by: Keerthy <j-keerthy@ti.com>
>>
>> Unfortunately, this patch has dependency [1] and can't be used alone as
>> it will cause ARM Global timer to be selected as clocksource
>> always on am437x and this will kill cpuidle, because ARM Global timer
>> is not in always_on domain.
>>
>> The intention of enabling ARM Global timer is only for non-pm aware use
>> cases for RT-kernel latency improvement - where deep cpuidle states are not
>> enabled.
>
> Yeah we need to fix up things to be able to change the clocksource
> in addition to clockevent. However, currently only cpuidle_coupled
> knows when the whole system is idle, so quite a bit of work is
> needed to do that in a sane way.

Also sched_clock and timer_delay ;)


>
> What about the first patch in this series?
>

Fist one is ok. It was originally posted long time ago.

--
regards,
-grygorii

\
 
 \ /
  Last update: 2016-12-02 21:02    [W:0.077 / U:0.820 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site