[PATCH v6] ARM: EXYNOS: Use MCPM call-backs to support S2R on Exynos5420

[Abhilash Kesavan]

Hi Nicolas,

On Sat, Jul 5, 2014 at 12:00 AM, Nicolas Pitre <nicolas.pitre at linaro.org> wrote:
> On Fri, 4 Jul 2014, Abhilash Kesavan wrote:
>
>> On Fri, Jul 4, 2014 at 9:43 AM, Nicolas Pitre <nicolas.pitre at 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.kesavan at 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));
>  }
Ah, I get it, much nicer indeed. Will change.
>
>
> Nicolas