linux-kernel - Re: [PATCH v10 01/27] PM / Domains: Add generic data pointer to genpd_power

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Date:   Tue, 18 Dec 2018 11:39:14 +0100
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Ulf Hansson <ulf.hansson@...aro.org>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Sudeep Holla <sudeep.holla@....com>,
        Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
        Mark Rutland <mark.rutland@....com>, linux-pm@...r.kernel.org
Cc:     "Raju P . L . S . S . S . N" <rplsssn@...eaurora.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Tony Lindgren <tony@...mide.com>,
        Kevin Hilman <khilman@...nel.org>,
        Lina Iyer <ilina@...eaurora.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        linux-arm-kernel@...ts.infradead.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v10 01/27] PM / Domains: Add generic data pointer to
 genpd_power_state struct

On 29/11/2018 18:46, Ulf Hansson wrote:
> Let's add a data pointer to the genpd_power_state struct, to allow a genpd
> backend driver to store per state specific data. In order to introduce the
> pointer, we also need to adopt how genpd frees the allocated data for the
> default genpd_power_state struct, that it may allocate at pm_genpd_init().
> 
> More precisely, let's use an internal genpd flag to understand when the
> states needs to be freed by genpd. When freeing the states data in
> genpd_remove(), let's also clear the corresponding genpd->states pointer
> and reset the genpd->state_count. In this way, a genpd backend driver
> becomes aware of when there is state specific data for it to free.
> 
> Cc: Lina Iyer <ilina@...eaurora.org>
> Co-developed-by: Lina Iyer <lina.iyer@...aro.org>
> Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
> ---
> 
> Changes in v10:
> 	- Update the patch allow backend drivers to free the states specific
> 	  data during genpd removal. Due to this added complexity, I decided to
> 	  keep the patch separate, rather than fold it into the patch that makes
> 	  use of the new void pointer, which was suggested by Rafael.
> 	- Claim authorship of the patch as lots of changes has been done since
> 	  the original pick up from Lina Iyer.
> 
> ---
>  drivers/base/power/domain.c | 8 ++++++--
>  include/linux/pm_domain.h   | 3 ++-
>  2 files changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index 7f38a92b444a..e27b91d36a2a 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -1620,7 +1620,7 @@ static int genpd_set_default_power_state(struct generic_pm_domain *genpd)
>  
>  	genpd->states = state;
>  	genpd->state_count = 1;
> -	genpd->free = state;
> +	genpd->free_state = true;
>  
>  	return 0;
>  }
> @@ -1736,7 +1736,11 @@ static int genpd_remove(struct generic_pm_domain *genpd)
>  	list_del(&genpd->gpd_list_node);
>  	genpd_unlock(genpd);
>  	cancel_work_sync(&genpd->power_off_work);
> -	kfree(genpd->free);
> +	if (genpd->free_state) {
> +		kfree(genpd->states);
> +		genpd->states = NULL;
> +		genpd->state_count = 0;

Why these two initializations? After genpd_remove, this structure
shouldn't be used anymore, no ?

> +	}

Instead of a flag, replacing the 'free' pointer to a 'free' callback
will allow to keep the free path self-encapsulated in domain.c

genpd->free(genpd->states);

Patch 18/27 can fill this field with its specific free pointer.



>  	pr_debug("%s: removed %s\n", __func__, genpd->name);
>  
>  	return 0;
> diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
> index 3b5d7280e52e..f9e09bd4152c 100644
> --- a/include/linux/pm_domain.h
> +++ b/include/linux/pm_domain.h
> @@ -69,6 +69,7 @@ struct genpd_power_state {
>  	s64 residency_ns;
>  	struct fwnode_handle *fwnode;
>  	ktime_t idle_time;
> +	void *data;
>  };
>  
>  struct genpd_lock_ops;
> @@ -110,7 +111,7 @@ struct generic_pm_domain {
>  	struct genpd_power_state *states;
>  	unsigned int state_count; /* number of states */
>  	unsigned int state_idx; /* state that genpd will go to when off */
> -	void *free; /* Free the state that was allocated for default */
> +	bool free_state; /* Free the state that was allocated for default */
>  	ktime_t on_time;
>  	ktime_t accounting_time;
>  	const struct genpd_lock_ops *lock_ops;
> 


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