Re: [PATCH v7 2/3] PM / Domains: Add support for 'required-opps' to set default perf state

[Ulf Hansson]

On Thu, 12 Aug 2021 at 13:28, Rajendra Nayak <rnayak@xxxxxxxxxxxxxx> wrote:
>
> Some devices within power domains with performance states do not
> support DVFS, but still need to vote on a default/static state
> while they are active. They can express this using the 'required-opps'
> property in device tree, which points to the phandle of the OPP
> supported by the corresponding power-domains.
>
> Add support to parse this information from DT and then set the
> specified performance state during attach and drop it on detach.
> runtime suspend/resume callbacks already have logic to drop/set
> the vote as needed and should take care of dropping the default
> perf state vote on runtime suspend and restore it back on runtime
> resume.
>
> Signed-off-by: Rajendra Nayak <rnayak@xxxxxxxxxxxxxx>

Reviewed-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>

Kind regards
Uffe


> ---
>  drivers/base/power/domain.c | 30 ++++++++++++++++++++++++++++--
>  include/linux/pm_domain.h   |  1 +
>  2 files changed, 29 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index a934c67..e1c8994 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -2598,6 +2598,12 @@ static void genpd_dev_pm_detach(struct device *dev, bool power_off)
>
>         dev_dbg(dev, "removing from PM domain %s\n", pd->name);
>
> +       /* Drop the default performance state */
> +       if (dev_gpd_data(dev)->default_pstate) {
> +               dev_pm_genpd_set_performance_state(dev, 0);
> +               dev_gpd_data(dev)->default_pstate = 0;
> +       }
> +
>         for (i = 1; i < GENPD_RETRY_MAX_MS; i <<= 1) {
>                 ret = genpd_remove_device(pd, dev);
>                 if (ret != -EAGAIN)
> @@ -2637,6 +2643,7 @@ static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev,
>  {
>         struct of_phandle_args pd_args;
>         struct generic_pm_domain *pd;
> +       int pstate;
>         int ret;
>
>         ret = of_parse_phandle_with_args(dev->of_node, "power-domains",
> @@ -2675,10 +2682,29 @@ static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev,
>                 genpd_unlock(pd);
>         }
>
> -       if (ret)
> +       if (ret) {
>                 genpd_remove_device(pd, dev);
> +               return -EPROBE_DEFER;
> +       }
>
> -       return ret ? -EPROBE_DEFER : 1;
> +       /* Set the default performance state */
> +       pstate = of_get_required_opp_performance_state(dev->of_node, index);
> +       if (pstate < 0 && pstate != -ENODEV) {
> +               ret = pstate;
> +               goto err;
> +       } else if (pstate > 0) {
> +               ret = dev_pm_genpd_set_performance_state(dev, pstate);
> +               if (ret)
> +                       goto err;
> +               dev_gpd_data(dev)->default_pstate = pstate;
> +       }
> +       return 1;
> +
> +err:
> +       dev_err(dev, "failed to set required performance state for power-domain %s: %d\n",
> +               pd->name, ret);
> +       genpd_remove_device(pd, dev);
> +       return ret;
>  }
>
>  /**
> diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
> index 21a0577..67017c9 100644
> --- a/include/linux/pm_domain.h
> +++ b/include/linux/pm_domain.h
> @@ -198,6 +198,7 @@ struct generic_pm_domain_data {
>         struct notifier_block *power_nb;
>         int cpu;
>         unsigned int performance_state;
> +       unsigned int default_pstate;
>         unsigned int rpm_pstate;
>         ktime_t next_wakeup;
>         void *data;
> --
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>