Re: [PATCH v4] clocksource: arm_global_timer: fix suspend resume

[Grygorii Strashko]

Hi All,
On 11/30/2015 08:25 PM, 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 (CPUIdle not enabled) - SysRq are 
> working,
> but nothing else.
> 
> 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)
>if not enabled.
> 
> CC: Arnd Bergmann 
> Cc: John Stultz 
> Cc: Felipe Balbi 
> Cc: Tony Lindgren 
> Cc: Marc Zyngier 
> Reviewed-by: Santosh Shilimkar 
> Signed-off-by: Grygorii Strashko 

Are there any comments? Do I need to perform any additional actions to have it 
merged?



-- 
regards,
-grygorii
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[PATCH v4] clocksource: arm_global_timer: fix suspend resume

[Grygorii Strashko]

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 (CPUIdle not enabled) - SysRq are 
working,
but nothing else.

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)
  if not enabled.

CC: Arnd Bergmann 
Cc: John Stultz 
Cc: Felipe Balbi 
Cc: Tony Lindgren 
Cc: Marc Zyngier 
Reviewed-by: Santosh Shilimkar 
Signed-off-by: Grygorii Strashko 
---
Changes in v4:
 - check current timer's state before enabling.
Changes in v3:
 - dropped all DT specific code
Changes in v2:
 - suspend/resume simplified: nothing is stored any more and
   ARM GT just re-enabled
Links on prev versions:
v3: https://lkml.org/lkml/2015/11/27/402
v2: https://lkml.org/lkml/2015/11/20/355
v1: https://lkml.org/lkml/2015/11/13/456

 drivers/clocksource/arm_global_timer.c | 11 +++
 1 file changed, 11 insertions(+)

diff --git a/drivers/clocksource/arm_global_timer.c 
b/drivers/clocksource/arm_global_timer.c
index a2cb6fa..817a787 100644
--- a/drivers/clocksource/arm_global_timer.c
+++ b/drivers/clocksource/arm_global_timer.c
@@ -195,12 +195,23 @@ static cycle_t gt_clocksource_read(struct clocksource *cs)
return gt_counter_read();
 }
 
+static void gt_resume(struct clocksource *cs)
+{
+   unsigned long ctrl;
+
+   ctrl = readl(gt_base + GT_CONTROL);
+   if (!(ctrl & GT_CONTROL_TIMER_ENABLE))
+   /* re-enable timer on resume */
+   writel(GT_CONTROL_TIMER_ENABLE, gt_base + GT_CONTROL);
+}
+
 static struct clocksource gt_clocksource = {
.name   = "arm_global_timer",
.rating = 300,
.read   = gt_clocksource_read,
.mask   = CLOCKSOURCE_MASK(64),
.flags  = CLOCK_SOURCE_IS_CONTINUOUS,
+   .resume = gt_resume,
 };
 
 #ifdef CONFIG_CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK
-- 
2.6.3

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