linux-kernel - Re: [PATCH] opp: Return genpd virtual devices from dev_pm_opp_attach

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Date:   Tue, 16 Jul 2019 12:43:54 +0200
From:   Niklas Cassel <niklas.cassel@...aro.org>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>, linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] opp: Return genpd virtual devices from
 dev_pm_opp_attach_genpd()

On Mon, Jul 08, 2019 at 11:30:11AM +0530, Viresh Kumar wrote:
> The cpufreq drivers don't need to do runtime PM operations on the
> virtual devices returned by dev_pm_domain_attach_by_name() and so the
> virtual devices weren't shared with the callers of
> dev_pm_opp_attach_genpd() earlier.
> 
> But the IO device drivers would want to do that. This patch updates the
> prototype of dev_pm_opp_attach_genpd() to accept another argument to
> return the pointer to the array of genpd virtual devices.
> 
> Reported-by: Rajendra Nayak <rnayak@...eaurora.org>
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> ---
> @Rajendra: Can you please test this one ? I have only compile tested it.
> 
>  drivers/opp/core.c     | 5 ++++-
>  include/linux/pm_opp.h | 4 ++--
>  2 files changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index 2958cc7bbb58..07b6f1187b3b 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -1775,6 +1775,7 @@ static void _opp_detach_genpd(struct opp_table *opp_table)
>   * dev_pm_opp_attach_genpd - Attach genpd(s) for the device and save virtual device pointer
>   * @dev: Consumer device for which the genpd is getting attached.
>   * @names: Null terminated array of pointers containing names of genpd to attach.
> + * @virt_devs: Pointer to return the array of virtual devices.
>   *
>   * Multiple generic power domains for a device are supported with the help of
>   * virtual genpd devices, which are created for each consumer device - genpd
> @@ -1789,7 +1790,8 @@ static void _opp_detach_genpd(struct opp_table *opp_table)
>   * This helper needs to be called once with a list of all genpd to attach.
>   * Otherwise the original device structure will be used instead by the OPP core.
>   */
> -struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **names)
> +struct opp_table *dev_pm_opp_attach_genpd(struct device *dev,
> +		const char **names, struct device ***virt_devs)
>  {
>  	struct opp_table *opp_table;
>  	struct device *virt_dev;
> @@ -1850,6 +1852,7 @@ struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **names
>  		name++;
>  	}
>  
> +	*virt_devs = opp_table->genpd_virt_devs;

Could we perhaps only do this if (virt_devs), that way callers can send in
NULL if they don't care about the genpd virtual devices.

Kind regards,
Niklas

>  	mutex_unlock(&opp_table->genpd_virt_dev_lock);
>  
>  	return opp_table;
> diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h
> index be570761b77a..7c2fe2952f40 100644
> --- a/include/linux/pm_opp.h
> +++ b/include/linux/pm_opp.h
> @@ -131,7 +131,7 @@ struct opp_table *dev_pm_opp_set_clkname(struct device *dev, const char * name);
>  void dev_pm_opp_put_clkname(struct opp_table *opp_table);
>  struct opp_table *dev_pm_opp_register_set_opp_helper(struct device *dev, int (*set_opp)(struct dev_pm_set_opp_data *data));
>  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);
> +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);
>  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);
> @@ -295,7 +295,7 @@ static inline struct opp_table *dev_pm_opp_set_clkname(struct device *dev, const
>  
>  static inline void dev_pm_opp_put_clkname(struct opp_table *opp_table) {}
>  
> -static inline struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **names)
> +static inline struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **names, struct device ***virt_devs)
>  {
>  	return ERR_PTR(-ENOTSUPP);
>  }
> -- 
> 2.21.0.rc0.269.g1a574e7a288b
>