Re: [PATCH v3 4/5] s390/idle: Introduce cpuidle for s390

[Heiko Carstens <hca@linux.ibm.com>]

On Thu, Jun 18, 2026 at 02:00:18PM +0200, Mete Durlu wrote:
> Introduce generic cpuidle driver on s390. Use a two stage approach to
> handle idle scenarios and use idle governor for idle stage selection.
> Two stages are, from shallow to deep, idle polling and enabled wait.
> 
> Suggested-by: Christian Borntraeger <borntraeger@linux.ibm.com>
> Suggested-by: Heiko Carstens <hca@linux.ibm.com>
> Signed-off-by: Mete Durlu <meted@linux.ibm.com>
> ---
>  MAINTAINERS                    |   8 +++
>  arch/s390/Kconfig              |   5 ++
>  drivers/cpuidle/Kconfig        |   5 ++
>  drivers/cpuidle/Kconfig.s390   |  11 ++++
>  drivers/cpuidle/Makefile       |   4 ++
>  drivers/cpuidle/cpuidle-s390.c | 115 +++++++++++++++++++++++++++++++++++++++++
>  6 files changed, 148 insertions(+)

...

> +static void __init s390_cpuidle_ew_tune(void)
> +{
> +	struct cpuidle_state *state = &s390_cpuidle_driver.states[1];
> +
> +	if (machine_is_lpar()) {
> +		state->target_residency = 5;
> +		state->exit_latency = 5;
> +	} else {
> +		state->target_residency = 1;
> +		state->exit_latency = 1;
> +	}
> +}

My Reviewed-by from the previous version still stands. However minor thing is
that this function should be renamed to something like s390_cpuidle_ew_init()
or s390_cpuidle_ew_setup().

But that's something Alexander can do when applying. Or it stays like it
is. Not too important.

Anyway:

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>