Hi Krzysztof,
On 13.05.2014 16:12, Krzysztof Kozlowski wrote:
> On Exynos4212 USE_DELAYED_RESET_ASSERTION must be set in
> ARM_CORE1_OPTION register during CPU power down. This is the proper way
> of powering down CPU. Additionally without this the CPU clock down won't
> work after powering down CPU1 and CPU will work at full frequency chosen
> by CPUfreq governor.
>
> Signed-off-by: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx>
> ---
> arch/arm/mach-exynos/hotplug.c | 28 +++++++++++++++++++++++++---
> arch/arm/mach-exynos/regs-pmu.h | 2 ++
> 2 files changed, 27 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm/mach-exynos/hotplug.c b/arch/arm/mach-exynos/hotplug.c
> index 5eead530c6f8..59b813e74558 100644
> --- a/arch/arm/mach-exynos/hotplug.c
> +++ b/arch/arm/mach-exynos/hotplug.c
> @@ -74,7 +74,7 @@ static inline void cpu_enter_lowpower_a15(void)
> dsb();
> }
>
> -static inline void cpu_leave_lowpower(void)
> +static inline void cpu_leave_lowpower(unsigned int cpu)
> {
> unsigned int v;
>
> @@ -88,6 +88,14 @@ static inline void cpu_leave_lowpower(void)
> : "=&r" (v)
> : "Ir" (CR_C), "Ir" (0x40)
> : "cc");
> +
> + if (cpu == 1 && soc_is_exynos4212()) {
AFAIK this is needed not only on Exynos4x12, but at least also on 4412.
Also I don't think the (cpu == 1) condition is necessary. See below.
> + unsigned int tmp;
> +
> + tmp = __raw_readl(S5P_ARM_CORE1_OPTION);
> + tmp &= ~(S5P_USE_DELAYED_RESET_ASSERTION);
> + __raw_writel(tmp, S5P_ARM_CORE1_OPTION);
> + }
> }
>
> static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
> @@ -95,8 +103,22 @@ static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
> for (;;) {
>
> /* make cpu1 to be turned off at next WFI command */
> - if (cpu == 1)
> + if (cpu == 1) {
I think this patch should be rebased on top of my "[PATCH] ARM: EXYNOS:
Fix core ID used by platsmp and hotplug code". Then instead of if (cpu
== 1) you would just use EXYNOS_ARM_CORE_OPTION(core_id).
Also same comment as above, I believe this is also needed on Exynos4412.
Best regards,
Tomasz
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