On Fri, 4 Jul 2014, Abhilash Kesavan wrote:

> On Fri, Jul 4, 2014 at 9:43 AM, Nicolas Pitre <nicolas.pi...@linaro.org> 
> wrote:
> > Another suggestion which might possibly be better: why not looking for
> > the SYS_PWR_CFG bit in exynos_cpu_power_down() directly?  After all,
> > exynos_cpu_power_down() is semantically supposed to do what its name
> > suggest and could simply do nothing if the proper conditions are already
> > in place.
> I have implemented this and it works fine. Patch coming up.

On Fri, 4 Jul 2014, Abhilash Kesavan wrote:

> Use the MCPM layer to handle core suspend/resume on Exynos5420.
> Also, restore the entry address setup code post-resume.
> 
> Signed-off-by: Abhilash Kesavan <a.kesa...@samsung.com>
> ---
> Changes in v2:
>       - Made use of the MCPM suspend/powered_up call-backs
> Changes in v3:
>       - Used the residency value to indicate the entered state
> Changes in v4:
>       - Checked if MCPM has been enabled to prevent build error
> Changes in v5:
>       - Removed the MCPM flags and just used a local flag to
>       indicate that we are suspending.
> Changes in v6:
>       - Read the SYS_PWR_REG value to decide if we are suspending
>       the system.
>       - Restore the SYS_PWR_REG value post-resume.
>       - Modified the comments to reflect the first change.

[...]

> @@ -150,7 +153,15 @@ static void exynos_power_down(void)
>       BUG_ON(__mcpm_cluster_state(cluster) != CLUSTER_UP);
>       cpu_use_count[cpu][cluster]--;
>       if (cpu_use_count[cpu][cluster] == 0) {
> -             exynos_cpu_power_down(cpunr);
> +             /*
> +              * Bypass power down for CPU0 during suspend. Check for
> +              * the SYS_PWR_REG value to decide if we are suspending
> +              * the system.
> +              */
> +             temp = __raw_readl(pmu_base_addr +
> +                     EXYNOS5_ARM_CORE0_SYS_PWR_REG);
> +             if ((cpu != 0) || ((temp & S5P_CORE_LOCAL_PWR_EN) != 0))
> +                     exynos_cpu_power_down(cpunr);

Nah...  We're going in circles, aren't we?

What I suggested above is:

diff --git a/arch/arm/mach-exynos/pm.c b/arch/arm/mach-exynos/pm.c
index 67d383de61..0a48421860 100644
--- a/arch/arm/mach-exynos/pm.c
+++ b/arch/arm/mach-exynos/pm.c
@@ -110,6 +110,16 @@ static int exynos_irq_set_wake(struct irq_data *data, 
unsigned int state)
  */
 void exynos_cpu_power_down(int cpu)
 {
+       if (soc_is_exynos5250() && cpu == 0) {
+               /*
+                * Bypass power down for CPU0 during suspend. Check for
+                * the SYS_PWR_REG value to decide if we are suspending
+                * the system.
+                */
+               int val = __raw_readl(pmu_base_addr 
+EXYNOS5_ARM_CORE0_SYS_PWR_REG);
+               if (!(val & S5P_CORE_LOCAL_PWR_EN))
+                       return;
+       }
        __raw_writel(0, EXYNOS_ARM_CORE_CONFIGURATION(cpu));
 }


Nicolas
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