Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1274344

Re: [PATCH v2] clocksource: arm_global_timer: fix suspend resume

Show all headers | View raw

On 20/11/15 18:35, Grygorii Strashko wrote:
> Hi Santosh,
> 
> On 11/20/2015 07:23 PM, santosh shilimkar wrote:
>> + Thomas, Marc
>>
>> On 11/20/2015 5:57 AM, Grygorii Strashko wrote:
>>> Now the System stall is observed on TI AM437x based board
>>> (am437x-gp-evm) during resuming from System suspend when ARM Global
>>> timer is selected as clocksource device - SysRq are working, but
>>> nothing else. The reason of stall is that ARM Global timer loses its
>>> contexts.
>>>
>>> The reason of stall is that ARM Global timer loses its contexts during
>>> System suspend:
>>>     GT_CONTROL.TIMER_ENABLE = 0 (unbanked)
>>>     GT_COUNTERx = 0
>>>
>>> Hence, update ARM Global timer driver to reflect above behaviour
>>> - re-enable ARM Global timer on resume GT_CONTROL.TIMER_ENABLE = 1
>>> - ensure clocksource and clockevent devices have coresponding flags
>>>    (CLOCK_SOURCE_SUSPEND_NONSTOP and CLOCK_EVT_FEAT_C3STOP) set
>>>    depending on presence of "always-on" DT property.
>>>
>> Something which loses context in low power states can't be
>> called "always-on"
> 
> Sry, it's kinda new area for me and I could make mistakes.
> 
> While working on this patch I've:
>  - re-used implementation from ARM arch timer 
> commit 82a5619410d4c4df65c04272db198eca5a867c18
> Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> Date:   Tue Apr 8 10:04:32 2014 +0100
> 
>     clocksource: arch_arm_timer: Fix age-old arch timer C3STOP detection issue

[...]

This patch has a very specific purpose: instructing the core code that
this timer will never stop ticking, ever. It is really targeted at
virtual machines, whose timer is backed by the host timer, even when the
VM is not running.

Using it on actual hardware is may not be the best idea, specially in
the presence of PM.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH v2] clocksource: arm_global_timer: fix suspend resume Grygorii Strashko <grygorii.strashko@ti.com> - 2015-11-20 15:00 +0100
  Re: [PATCH v2] clocksource: arm_global_timer: fix suspend resume santosh shilimkar <santosh.shilimkar@oracle.com> - 2015-11-20 18:30 +0100
    Re: [PATCH v2] clocksource: arm_global_timer: fix suspend resume Grygorii Strashko <grygorii.strashko@ti.com> - 2015-11-20 19:40 +0100
      Re: [PATCH v2] clocksource: arm_global_timer: fix suspend resume Marc Zyngier <marc.zyngier@arm.com> - 2015-11-20 19:50 +0100
        Re: [PATCH v2] clocksource: arm_global_timer: fix suspend resume santosh shilimkar <santosh.shilimkar@oracle.com> - 2015-11-20 20:00 +0100
          Re: [PATCH v2] clocksource: arm_global_timer: fix suspend resume Grygorii Strashko <grygorii.strashko@ti.com> - 2015-11-20 20:20 +0100
        Re: [PATCH v2] clocksource: arm_global_timer: fix suspend resume John Stultz <john.stultz@linaro.org> - 2015-11-20 20:20 +0100
      Re: [PATCH v2] clocksource: arm_global_timer: fix suspend resume John Stultz <john.stultz@linaro.org> - 2015-11-20 20:10 +0100
        Re: [PATCH v2] clocksource: arm_global_timer: fix suspend resume Grygorii Strashko <grygorii.strashko@ti.com> - 2015-11-20 20:30 +0100
          Re: [PATCH v2] clocksource: arm_global_timer: fix suspend resume John Stultz <john.stultz@linaro.org> - 2015-11-20 20:40 +0100
            Re: [PATCH v2] clocksource: arm_global_timer: fix suspend resume Grygorii Strashko <grygorii.strashko@ti.com> - 2015-11-20 21:50 +0100
        Re: [PATCH v2] clocksource: arm_global_timer: fix suspend resume Thomas Gleixner <tglx@linutronix.de> - 2015-11-20 20:30 +0100

csiph-web