linux-kernel - Re: [PATCH v3 2/5] OPP: Add function to look up required OPP's for a given OPP

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Message-ID: <20190723095316.t5ltprixxd5veuj7@vireshk-i7>
Date:   Tue, 23 Jul 2019 15:23:16 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Saravana Kannan <saravanak@...gle.com>
Cc:     MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Sibi Sankar <sibis@...eaurora.org>, kernel-team@...roid.com,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/5] OPP: Add function to look up required OPP's for a
 given OPP

On 17-07-19, 15:23, Saravana Kannan wrote:
> Add a function that allows looking up required OPPs given a source OPP
> table, destination OPP table and the source OPP.
> 
> Signed-off-by: Saravana Kannan <saravanak@...gle.com>
> ---
>  drivers/opp/core.c     | 54 ++++++++++++++++++++++++++++++++++++++++++
>  include/linux/pm_opp.h | 11 +++++++++
>  2 files changed, 65 insertions(+)
> 
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index 438fcd134d93..72c055a3f6b7 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -1883,6 +1883,60 @@ void dev_pm_opp_detach_genpd(struct opp_table *opp_table)
>  }
>  EXPORT_SYMBOL_GPL(dev_pm_opp_detach_genpd);
>  
> +/**
> + * dev_pm_opp_xlate_opp() - Find required OPP for src_table OPP.
> + * @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: OPP of the src_table.

You should use @ before parameters in the comments as well ? Just like
you did that below.

> + *
> + * This function returns the OPP (present in @dst_table) pointed out by the
> + * "required-opps" property of the OPP (present in @src_table).
> + *
> + * The callers are required to call dev_pm_opp_put() for the returned OPP after
> + * use.
> + *
> + * Return: destination table OPP on success, otherwise NULL on errors.
> + */
> +struct dev_pm_opp *dev_pm_opp_xlate_opp(struct opp_table *src_table,

Please name it dev_pm_opp_xlate_required_opp().

> +					struct opp_table *dst_table,
> +					struct dev_pm_opp *src_opp)
> +{
> +	struct dev_pm_opp *opp, *dest_opp = NULL;
> +	int i;
> +
> +	if (!src_table || !dst_table || !src_opp)
> +		return NULL;
> +
> +	for (i = 0; i < src_table->required_opp_count; i++) {
> +		if (src_table->required_opp_tables[i]->np == dst_table->np)

Why can't we just compare the table pointers instead ? Yeah, I know
that's how I wrote that in the other xlate function, but I am confused
now :)

> +			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 NULL;
> +	}
> +
> +	mutex_lock(&src_table->lock);
> +
> +	list_for_each_entry(opp, &src_table->opp_list, node) {
> +		if (opp == src_opp) {
> +			dest_opp = opp->required_opps[i];
> +			dev_pm_opp_get(dest_opp);
> +			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_opp;
> +}
> +
>  /**
>   * 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.
> diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h
> index af5021f27cb7..36f52b9cf24a 100644
> --- a/include/linux/pm_opp.h
> +++ b/include/linux/pm_opp.h
> @@ -131,6 +131,9 @@ void dev_pm_opp_unregister_set_opp_helper(struct opp_table *opp_table);
>  struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **names);
>  void dev_pm_opp_detach_genpd(struct opp_table *opp_table);
>  int dev_pm_opp_xlate_performance_state(struct opp_table *src_table, struct opp_table *dst_table, unsigned int pstate);
> +struct dev_pm_opp *dev_pm_opp_xlate_opp(struct opp_table *src_table,
> +					struct opp_table *dst_table,
> +					struct dev_pm_opp *src_opp);
>  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);
> @@ -304,6 +307,14 @@ static inline int dev_pm_opp_xlate_performance_state(struct opp_table *src_table
>  	return -ENOTSUPP;
>  }
>  
> +static inline struct dev_pm_opp *dev_pm_opp_xlate_opp(
> +						struct opp_table *src_table,
> +						struct opp_table *dst_table,
> +						struct dev_pm_opp *src_opp)
> +{
> +	return NULL;
> +}
> +

Keep the order of declaring routines same, so this goes before the
other xlate routine.

>  static inline int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq)
>  {
>  	return -ENOTSUPP;
> -- 
> 2.22.0.510.g264f2c817a-goog

-- 
viresh