linux-kernel - Re: [PATCH v5 1/3] OPP: Add function to look up required OPP's for a given OPP

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Date:   Thu, 4 Feb 2021 11:16:58 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Hsin-Yi Wang <hsinyi@...omium.org>
Cc:     Viresh Kumar <vireshk@...nel.org>, linux-pm@...r.kernel.org,
        Nishanth Menon <nm@...com>, Stephen Boyd <sboyd@...nel.org>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        linux-kernel@...r.kernel.org,
        "MyungJoo Ham )" <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Saravana Kannan <saravanak@...gle.com>
Subject: Re: [PATCH v5 1/3] OPP: Add function to look up required OPP's for a
 given OPP

On 03-02-21, 17:23, Hsin-Yi Wang wrote:
> From: Saravana Kannan <saravanak@...gle.com>
> 
> 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>
> Signed-off-by: Hsin-Yi Wang <hsinyi@...omium.org>
> ---
>  drivers/opp/core.c     | 58 ++++++++++++++++++++++++++++++++++++++++++
>  include/linux/pm_opp.h | 11 ++++++++
>  2 files changed, 69 insertions(+)
> 
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index dc95d29e94c1b..878f066b972cc 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -2398,6 +2398,64 @@ devm_pm_opp_attach_genpd(struct device *dev, const char **names,
>  }
>  EXPORT_SYMBOL_GPL(devm_pm_opp_attach_genpd);
>  
> +/**
> + * dev_pm_opp_xlate_required_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.
> + *
> + * 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_required_opp(struct opp_table *src_table,
> +						 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 ||
> +	    !src_table->required_opp_tables)
> +		return NULL;
> +
> +	/* required-opps not fully initialized yet */
> +	if (lazy_linking_pending(src_table))
> +		return NULL;
> +
> +	for (i = 0; i < src_table->required_opp_count; i++) {
> +		if (src_table->required_opp_tables[i] == dst_table)
> +			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 ab1d15ce559db..6f5f72a7f601c 100644
> --- a/include/linux/pm_opp.h
> +++ b/include/linux/pm_opp.h
> @@ -156,6 +156,9 @@ struct opp_table *devm_pm_opp_register_set_opp_helper(struct device *dev, int (*
>  struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **names, struct device ***virt_devs);
>  void dev_pm_opp_detach_genpd(struct opp_table *opp_table);
>  struct opp_table *devm_pm_opp_attach_genpd(struct device *dev, const char **names, struct device ***virt_devs);
> +struct dev_pm_opp *dev_pm_opp_xlate_required_opp(struct opp_table *src_table,
> +						 struct opp_table *dst_table,
> +						 struct dev_pm_opp *src_opp);
>  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_opp(struct device *dev, struct dev_pm_opp *opp);
> @@ -367,6 +370,14 @@ static inline struct opp_table *devm_pm_opp_attach_genpd(struct device *dev,
>  	return ERR_PTR(-EOPNOTSUPP);
>  }
>  
> +static inline struct dev_pm_opp *dev_pm_opp_xlate_required_opp(
> +						struct opp_table *src_table,
> +						struct opp_table *dst_table,
> +						struct dev_pm_opp *src_opp)
> +{
> +	return NULL;
> +}

Like other routines that return opp *, don't return NULL on errors but
a valid error number instead. And follow the declaration format of
other routines from this file, don't break lines etc.. 

> +
>  static inline int dev_pm_opp_xlate_performance_state(struct opp_table *src_table, struct opp_table *dst_table, unsigned int pstate)
>  {
>  	return -EOPNOTSUPP;
> -- 
> 2.30.0.365.g02bc693789-goog

-- 
viresh