* Grygorii Strashko <grygorii.stras...@ti.com> [151214 12:35]:
> System will misbehave in the following case:
> - AM43XX only build (UP);
> - CONFIG_CPU_IDLE=y
> - ARM TWD timer enabled and selected as clockevent device.
>
> In the above case, It's expected that broadcast timer will be used as
> backup timer when CPUIdle will put MPU in low power states where ARM
> TWD will stop and lose its context. But, the CONFIG_SMP might not be
> selected when kernel is built for AM43XX SoC only and, as result,
> GENERIC_CLOCKEVENTS_BROADCAST option will not be selected also. This
> will break CPUIdle and System will stuck in low power states.
>
> Hence, fix it by selecting GENERIC_CLOCKEVENTS_BROADCAST option for
> AM43XX SoCs always and add empty tick_broadcast() function
> implementation - no need to send any IPI on UP. After this change
> timer1 will be selected as broadcast timer the same way as for SMP,
> and CPUIdle will work properly.
I've applied both of these into omap-for-v4.4/fixes because of the
description above.
Regards,
Tony
>
> Signed-off-by: Grygorii Strashko <grygorii.stras...@ti.com>
> ---
> arch/arm/mach-omap2/Kconfig | 1 +
> arch/arm/mach-omap2/timer.c | 6 ++++++
> 2 files changed, 7 insertions(+)
>
> diff --git a/arch/arm/mach-omap2/Kconfig b/arch/arm/mach-omap2/Kconfig
> index 4b4371d..32a0086 100644
> --- a/arch/arm/mach-omap2/Kconfig
> +++ b/arch/arm/mach-omap2/Kconfig
> @@ -65,6 +65,7 @@ config SOC_AM43XX
> select MACH_OMAP_GENERIC
> select MIGHT_HAVE_CACHE_L2X0
> select HAVE_ARM_SCU
> + select GENERIC_CLOCKEVENTS_BROADCAST
>
> config SOC_DRA7XX
> bool "TI DRA7XX"
> diff --git a/arch/arm/mach-omap2/timer.c b/arch/arm/mach-omap2/timer.c
> index 3bfde44..f34a809 100644
> --- a/arch/arm/mach-omap2/timer.c
> +++ b/arch/arm/mach-omap2/timer.c
> @@ -320,6 +320,12 @@ static int __init omap_dm_timer_init_one(struct
> omap_dm_timer *timer,
> return r;
> }
>
> +#if !defined(CONFIG_SMP) && defined(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST)
> +void tick_broadcast(const struct cpumask *mask)
> +{
> +}
> +#endif
> +
> static void __init omap2_gp_clockevent_init(int gptimer_id,
> const char *fck_source,
> const char *property)
> --
> 2.6.4
>
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