[Letux-kernel] [PATCH] omap5: Enable tick broadcasts in low power mode

[David Shah]

Seems I spoke too soon, it did eventually lock up with this added -
although it did seem to make things more reliable. Wondering if there
is still some benefit to adding it, or whether it is just coincidence
that it made things more stable (anything that adds delay to switching
in/out of retention mode seems to improve stability, which makes it
hard to debug...)

Best

David

On Wed, 2020-08-05 at 16:59 +0100, David Shah wrote:
> Seems to fix some occasional random lockups. The original TI code
> does something analagous to this.
> 
> Signed-off-by: David Shah <dave at ds0.me>
> ---
>  arch/arm/mach-omap2/cpuidle44xx.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/arch/arm/mach-omap2/cpuidle44xx.c b/arch/arm/mach-
> omap2/cpuidle44xx.c
> index de94173ce531..5b4befb1c5ae 100644
> --- a/arch/arm/mach-omap2/cpuidle44xx.c
> +++ b/arch/arm/mach-omap2/cpuidle44xx.c
> @@ -110,6 +110,12 @@ static int omap_enter_idle_smp(struct
> cpuidle_device *dev,
>  	struct idle_statedata *cx = state_ptr + index;
>  	unsigned long flag;
>  
> +	/* Enter broadcast mode for periodic timers */
> +	tick_broadcast_enable();
> +
> +	/* Enter broadcast mode for one-shot timers */
> +	tick_broadcast_enter();
> +
>  	raw_spin_lock_irqsave(&mpu_lock, flag);
>  	cx->mpu_state_vote++;
>  	if (cx->mpu_state_vote == num_online_cpus()) {
> @@ -126,6 +132,8 @@ static int omap_enter_idle_smp(struct
> cpuidle_device *dev,
>  	cx->mpu_state_vote--;
>  	raw_spin_unlock_irqrestore(&mpu_lock, flag);
>  
> +	tick_broadcast_exit();
> +
>  	return index;
>  }
>