[PATCH] pmdomain: arm: scmi_pm_domain: Remove redundant state verification

[Ulf Hansson]

On Fri, 14 Mar 2025 at 10:58, Sudeep Holla <sudeep.holla at arm.com> wrote:
>
> Currently, scmi_pd_power() explicitly verifies whether the requested
> power state was applied by calling state_get(). While this check could
> detect failures where the state was not properly updated, ensuring
> correctness is the responsibility of the SCMI firmware.
>
> Removing this redundant state_get() call eliminates an unnecessary
> round-trip to the firmware, improving efficiency. Any mismatches
> between the requested and actual states should be handled by the SCMI
> firmware, which must return a failure if state_set() is unsuccessful.
>
> Additionally, in some cases, checking the state after powering off a
> domain may be unreliable or unsafe, depending on the firmware
> implementation.
>
> This patch removes the redundant verification, simplifying the function
> without compromising correctness.
>
> Cc: Peng Fan <peng.fan at nxp.com>
> Cc: Ulf Hansson <ulf.hansson at linaro.org>
> Cc: Cristian Marussi <cristian.marussi at arm.com>
> Reported-and-tested-by: Ranjani Vaidyanathan <ranjani.vaidyanathan at nxp.com>
> Signed-off-by: Sudeep Holla <sudeep.holla at arm.com>

Applied for next, thanks!

Kind regards
Uffe


> ---
>  drivers/pmdomain/arm/scmi_pm_domain.c | 11 ++---------
>  1 file changed, 2 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/pmdomain/arm/scmi_pm_domain.c b/drivers/pmdomain/arm/scmi_pm_domain.c
> index 86b531e15b85..2a213c218126 100644
> --- a/drivers/pmdomain/arm/scmi_pm_domain.c
> +++ b/drivers/pmdomain/arm/scmi_pm_domain.c
> @@ -24,8 +24,7 @@ struct scmi_pm_domain {
>
>  static int scmi_pd_power(struct generic_pm_domain *domain, bool power_on)
>  {
> -       int ret;
> -       u32 state, ret_state;
> +       u32 state;
>         struct scmi_pm_domain *pd = to_scmi_pd(domain);
>
>         if (power_on)
> @@ -33,13 +32,7 @@ static int scmi_pd_power(struct generic_pm_domain *domain, bool power_on)
>         else
>                 state = SCMI_POWER_STATE_GENERIC_OFF;
>
> -       ret = power_ops->state_set(pd->ph, pd->domain, state);
> -       if (!ret)
> -               ret = power_ops->state_get(pd->ph, pd->domain, &ret_state);
> -       if (!ret && state != ret_state)
> -               return -EIO;
> -
> -       return ret;
> +       return power_ops->state_set(pd->ph, pd->domain, state);
>  }
>
>  static int scmi_pd_power_on(struct generic_pm_domain *domain)
> --
> 2.34.1
>