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[PATCH v4 2/2] ARM: cpuidle: make arm_cpuidle_suspend() a bit more efficient

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  [PATCH v4 2/2] ARM: cpuidle: make arm_cpuidle_suspend() a bit more efficient Jisheng Zhang <jszhang@marvell.com> - 2016-07-06 08:30 +0200
    Re: [PATCH v4 2/2] ARM: cpuidle: make arm_cpuidle_suspend() a bit  more efficient Daniel Lezcano <daniel.lezcano@linaro.org> - 2016-07-07 15:50 +0200
      Re: [PATCH v4 2/2] ARM: cpuidle: make arm_cpuidle_suspend() a bit  more efficient Jisheng Zhang <jszhang@marvell.com> - 2016-07-08 08:30 +0200
        Re: [PATCH v4 2/2] ARM: cpuidle: make arm_cpuidle_suspend() a bit  more efficient Daniel Lezcano <daniel.lezcano@linaro.org> - 2016-07-08 13:00 +0200
          Re: [PATCH v4 2/2] ARM: cpuidle: make arm_cpuidle_suspend() a bit  more efficient Jisheng Zhang <jszhang@marvell.com> - 2016-07-08 13:10 +0200

#1437471 — [PATCH v4 2/2] ARM: cpuidle: make arm_cpuidle_suspend() a bit more efficient

Currently, we check cpuidle_ops.suspend every time when entering a
low-power idle state. But this check could be avoided in this hot path
by moving it into arm_cpuidle_read_ops() to reduce arm_cpuidle_suspend
overhead a bit.

Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
---
 arch/arm/kernel/cpuidle.c | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/arch/arm/kernel/cpuidle.c b/arch/arm/kernel/cpuidle.c
index 2129b29..7dccc96 100644
--- a/arch/arm/kernel/cpuidle.c
+++ b/arch/arm/kernel/cpuidle.c
@@ -47,18 +47,13 @@ int arm_cpuidle_simple_enter(struct cpuidle_device *dev,
  * This function calls the underlying arch specific low level PM code as
  * registered at the init time.
  *
- * Returns -EOPNOTSUPP if no suspend callback is defined, the result of the
- * callback otherwise.
+ * Returns the result of the suspend callback.
  */
 int arm_cpuidle_suspend(int index)
 {
-	int ret = -EOPNOTSUPP;
 	int cpu = smp_processor_id();
 
-	if (cpuidle_ops[cpu].suspend)
-		ret = cpuidle_ops[cpu].suspend(index);
-
-	return ret;
+	return cpuidle_ops[cpu].suspend(index);
 }
 
 /**
@@ -92,8 +87,8 @@ static const struct cpuidle_ops *__init arm_cpuidle_get_ops(const char *method)
  * process.
  *
  * Return 0 on sucess, -ENOENT if no 'enable-method' is defined, -EOPNOTSUPP if
- * no cpuidle_ops is registered for the 'enable-method', or if no init callback
- * is defined.
+ * no cpuidle_ops is registered for the 'enable-method', or if either init or
+ * suspend callback isn't defined.
  */
 static int __init arm_cpuidle_read_ops(struct device_node *dn, int cpu)
 {
@@ -111,8 +106,8 @@ static int __init arm_cpuidle_read_ops(struct device_node *dn, int cpu)
 		return -EOPNOTSUPP;
 	}
 
-	if (!ops->init) {
-		pr_warn("cpuidle_ops '%s': no init callback\n",
+	if (!ops->init || !ops->suspend) {
+		pr_warn("cpuidle_ops '%s': no init or suspend callback\n",
 			enable_method);
 		return -EOPNOTSUPP;
 	}
-- 
2.8.1

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#1438630 — Re: [PATCH v4 2/2] ARM: cpuidle: make arm_cpuidle_suspend() a bit more efficient

On Wed, Jul 06, 2016 at 02:15:55PM +0800, Jisheng Zhang wrote:
> Currently, we check cpuidle_ops.suspend every time when entering a
> low-power idle state. But this check could be avoided in this hot path
> by moving it into arm_cpuidle_read_ops() to reduce arm_cpuidle_suspend
> overhead a bit.
> 
> Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
> ---

Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>

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#1439140 — Re: [PATCH v4 2/2] ARM: cpuidle: make arm_cpuidle_suspend() a bit more efficient

Dear Daniel,

On Thu, 7 Jul 2016 15:46:28 +0200 Daniel Lezcano wrote:

> On Wed, Jul 06, 2016 at 02:15:55PM +0800, Jisheng Zhang wrote:
> > Currently, we check cpuidle_ops.suspend every time when entering a
> > low-power idle state. But this check could be avoided in this hot path
> > by moving it into arm_cpuidle_read_ops() to reduce arm_cpuidle_suspend
> > overhead a bit.
> > 
> > Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
> > ---  
> 
> Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>

I'm not sure the upstream merging path this patch should follow, Per my
understanding, I need to put it into Russell's PATCH system.

Thanks in advance,
Jisheng

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#1439292 — Re: [PATCH v4 2/2] ARM: cpuidle: make arm_cpuidle_suspend() a bit more efficient

On Fri, Jul 08, 2016 at 02:17:29PM +0800, Jisheng Zhang wrote:
> Dear Daniel,
> 
> On Thu, 7 Jul 2016 15:46:28 +0200 Daniel Lezcano wrote:
> 
> > On Wed, Jul 06, 2016 at 02:15:55PM +0800, Jisheng Zhang wrote:
> > > Currently, we check cpuidle_ops.suspend every time when entering a
> > > low-power idle state. But this check could be avoided in this hot path
> > > by moving it into arm_cpuidle_read_ops() to reduce arm_cpuidle_suspend
> > > overhead a bit.
> > > 
> > > Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
> > > ---  
> > 
> > Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
> 
> I'm not sure the upstream merging path this patch should follow, Per my
> understanding, I need to put it into Russell's PATCH system.

Or alternatively through arm-soc

  -- Daniel

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#1439298 — Re: [PATCH v4 2/2] ARM: cpuidle: make arm_cpuidle_suspend() a bit more efficient

On Fri, 8 Jul 2016 12:50:12 +0200 Daniel Lezcano  wrote:

> On Fri, Jul 08, 2016 at 02:17:29PM +0800, Jisheng Zhang wrote:
> > Dear Daniel,
> > 
> > On Thu, 7 Jul 2016 15:46:28 +0200 Daniel Lezcano wrote:
> >   
> > > On Wed, Jul 06, 2016 at 02:15:55PM +0800, Jisheng Zhang wrote:  
> > > > Currently, we check cpuidle_ops.suspend every time when entering a
> > > > low-power idle state. But this check could be avoided in this hot path
> > > > by moving it into arm_cpuidle_read_ops() to reduce arm_cpuidle_suspend
> > > > overhead a bit.
> > > > 
> > > > Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
> > > > ---    
> > > 
> > > Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>  
> > 
> > I'm not sure the upstream merging path this patch should follow, Per my
> > understanding, I need to put it into Russell's PATCH system.  
> 
> Or alternatively through arm-soc
> 

Got it. thanks.

Dear Arnd, Olof,

I have no pull request permission. what's your preference? Could you please
advise?

Thanks

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