Re: [PATCH V2 2/5] OPP: Add dev_pm_opp_xlate_performance_state() helper

[Ulf Hansson]

On Mon, 26 Nov 2018 at 09:10, Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote:
>
> Introduce a new helper dev_pm_opp_xlate_performance_state() which will
> be used to translate from pstate of a device to another one.

I don't get this, could you please elaborate?

>
> Initially this will be used by genpd to find pstate of a master domain
> using its sub-domain's pstate.

I assume pstate is the performance state of a genpd that you refer to,
no? Please try to be a bit more descriptive in your changelogs, to
avoid confusions.

>
> Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
> ---
>  drivers/opp/core.c     | 59 ++++++++++++++++++++++++++++++++++++++++++
>  include/linux/pm_opp.h |  7 +++++
>  2 files changed, 66 insertions(+)
>
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index 0eaa954b3f6c..99b71f60b6d8 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -1707,6 +1707,65 @@ void dev_pm_opp_put_genpd_virt_dev(struct opp_table *opp_table,
>                 dev_err(virt_dev, "Failed to find required device entry\n");
>  }
>
> +/**
> + * dev_pm_opp_xlate_performance_state() - Find required OPP's pstate for src_table.
> + * @src_table: OPP table which has dst_table as one of its required OPP table.
> + * @dst_table: Required OPP table of the src_table.
> + * @pstate: Current performance state of the src_table.
> + *
> + * This Returns pstate of the OPP (present in @dst_table) pointed out by the
> + * "required-opps" property of the OPP (present in @src_table) which has
> + * performance state set to @pstate.
> + *
> + * Return: Positive performance state on success, otherwise 0 on errors.
> + */
> +unsigned int dev_pm_opp_xlate_performance_state(struct opp_table *src_table,
> +                                               struct opp_table *dst_table,
> +                                               unsigned int pstate)
> +{
> +       struct dev_pm_opp *opp;
> +       unsigned int dest_pstate = 0;
> +       int i;
> +
> +       /*
> +        * Normally the src_table will have the "required_opps" property set to
> +        * point to one of the OPPs in the dst_table, but in some cases the
> +        * genpd and its master have one to one mapping of performance states
> +        * and so none of them have the "required-opps" property set. Return the
> +        * pstate of the src_table as it is in such cases.

This comment is good, but I also think some of this important
information is missing in the changelog.

> +        */
> +       if (!src_table->required_opp_count)
> +               return pstate;
> +
> +       for (i = 0; i < src_table->required_opp_count; i++) {
> +               if (src_table->required_opp_tables[i]->np == dst_table->np)
> +                       break;
> +       }
> +
> +       if (unlikely(i == src_table->required_opp_count)) {
> +               pr_err("%s: Couldn't find matching OPP table (%p: %p)\n",
> +                      __func__, src_table, dst_table);
> +               return 0;
> +       }
> +
> +       mutex_lock(&src_table->lock);
> +
> +       list_for_each_entry(opp, &src_table->opp_list, node) {
> +               if (opp->pstate == pstate) {
> +                       dest_pstate = opp->required_opps[i]->pstate;
> +                       goto unlock;
> +               }
> +       }
> +
> +       pr_err("%s: Couldn't find matching OPP (%p: %p)\n", __func__, src_table,
> +              dst_table);
> +
> +unlock:
> +       mutex_unlock(&src_table->lock);
> +
> +       return dest_pstate;
> +}
> +
>  /**
>   * dev_pm_opp_add()  - Add an OPP table from a table definitions
>   * @dev:       device for which we do this operation
> diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h
> index 2b2c3fd985ab..5a64a81a1789 100644
> --- a/include/linux/pm_opp.h
> +++ b/include/linux/pm_opp.h
> @@ -128,6 +128,7 @@ struct opp_table *dev_pm_opp_register_set_opp_helper(struct device *dev, int (*s
>  void dev_pm_opp_unregister_set_opp_helper(struct opp_table *opp_table);
>  struct opp_table *dev_pm_opp_set_genpd_virt_dev(struct device *dev, struct device *virt_dev, int index);
>  void dev_pm_opp_put_genpd_virt_dev(struct opp_table *opp_table, struct device *virt_dev);
> +unsigned int dev_pm_opp_xlate_performance_state(struct opp_table *src_table, struct opp_table *dst_table, unsigned int pstate);
>  int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq);
>  int dev_pm_opp_set_sharing_cpus(struct device *cpu_dev, const struct cpumask *cpumask);
>  int dev_pm_opp_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask);
> @@ -280,6 +281,12 @@ static inline struct opp_table *dev_pm_opp_set_genpd_virt_dev(struct device *dev
>  }
>
>  static inline void dev_pm_opp_put_genpd_virt_dev(struct opp_table *opp_table, struct device *virt_dev) {}
> +
> +static inline unsigned int dev_pm_opp_xlate_performance_state(struct opp_table *src_table, struct opp_table *dst_table, unsigned int pstate)
> +{
> +       return 0;
> +}
> +
>  static inline int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq)
>  {
>         return -ENOTSUPP;
> --
> 2.19.1.568.g152ad8e3369a
>

Besides the comments, I think this makes sense to me. Although, let me
review the rest in the series before making a final call.

Kind regards
Uffe