linux-kernel - Re: [PATCH 2/2] opp: Allocate genpd_virt_devs from dev_pm_opp_attach

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Date:   Mon, 13 May 2019 13:05:20 +0200
From:   Niklas Cassel <niklas.cassel@...aro.org>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Rafael Wysocki <rjw@...ysocki.net>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...nel.org>, linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Amit Kucheria <amit.kucheria@...aro.org>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] opp: Allocate genpd_virt_devs from
 dev_pm_opp_attach_genpd()

On Mon, May 13, 2019 at 03:54:11PM +0530, Viresh Kumar wrote:
> Currently the space for the array of virtual devices is allocated along
> with the OPP table, but that isn't going to work well from now onwards.
> For single power domain case, a driver can either use the original
> device structure for setting the performance state (if genpd attached
> with dev_pm_domain_attach()) or use the virtual device structure (if
> genpd attached with dev_pm_domain_attach_by_name(), which returns the
> virtual device) and so we can't know in advance if we are going to need
> genpd_virt_devs array or not.
> 
> Lets delay the allocation a bit and do it along with
> dev_pm_opp_attach_genpd() rather. The deallocation is done from
> dev_pm_opp_detach_genpd().
> 
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> ---
>  drivers/opp/core.c | 10 ++++++++++
>  drivers/opp/of.c   | 30 ++----------------------------
>  2 files changed, 12 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index 67d6b0caeab1..764e05a2fa66 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -1755,6 +1755,9 @@ static void _opp_detach_genpd(struct opp_table *opp_table)
>  		dev_pm_domain_detach(opp_table->genpd_virt_devs[index], false);
>  		opp_table->genpd_virt_devs[index] = NULL;
>  	}
> +
> +	kfree(opp_table->genpd_virt_devs);
> +	opp_table->genpd_virt_devs = NULL;
>  }
>  
>  /**
> @@ -1798,6 +1801,12 @@ struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **names
>  
>  	mutex_lock(&opp_table->genpd_virt_dev_lock);
>  
> +	opp_table->genpd_virt_devs = kcalloc(opp_table->required_opp_count,
> +					     sizeof(*opp_table->genpd_virt_devs),
> +					     GFP_KERNEL);
> +	if (!opp_table->genpd_virt_devs)
> +		goto unlock;
> +
>  	while (*name) {
>  		index = of_property_match_string(dev->of_node,
>  						 "power-domain-names", *name);
> @@ -1836,6 +1845,7 @@ struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **names
>  
>  err:
>  	_opp_detach_genpd(opp_table);
> +unlock:
>  	mutex_unlock(&opp_table->genpd_virt_dev_lock);
>  
>  put_table:
> diff --git a/drivers/opp/of.c b/drivers/opp/of.c
> index c10c782d15aa..a637f30552a3 100644
> --- a/drivers/opp/of.c
> +++ b/drivers/opp/of.c
> @@ -141,7 +141,6 @@ static struct opp_table *_find_table_of_opp_np(struct device_node *opp_np)
>  static void _opp_table_free_required_tables(struct opp_table *opp_table)
>  {
>  	struct opp_table **required_opp_tables = opp_table->required_opp_tables;
> -	struct device **genpd_virt_devs = opp_table->genpd_virt_devs;
>  	int i;
>  
>  	if (!required_opp_tables)
> @@ -155,10 +154,8 @@ static void _opp_table_free_required_tables(struct opp_table *opp_table)
>  	}
>  
>  	kfree(required_opp_tables);
> -	kfree(genpd_virt_devs);
>  
>  	opp_table->required_opp_count = 0;
> -	opp_table->genpd_virt_devs = NULL;
>  	opp_table->required_opp_tables = NULL;
>  }
>  
> @@ -171,9 +168,8 @@ static void _opp_table_alloc_required_tables(struct opp_table *opp_table,
>  					     struct device_node *opp_np)
>  {
>  	struct opp_table **required_opp_tables;
> -	struct device **genpd_virt_devs = NULL;
>  	struct device_node *required_np, *np;
> -	int count, count_pd, i;
> +	int count, i;
>  
>  	/* Traversing the first OPP node is all we need */
>  	np = of_get_next_available_child(opp_np, NULL);
> @@ -186,33 +182,11 @@ static void _opp_table_alloc_required_tables(struct opp_table *opp_table,
>  	if (!count)
>  		goto put_np;
>  
> -	/*
> -	 * Check the number of power-domains to know if we need to deal
> -	 * with virtual devices. In some cases we have devices with multiple
> -	 * power domains but with only one of them being scalable, hence
> -	 * 'count' could be 1, but we still have to deal with multiple genpds
> -	 * and virtual devices.
> -	 */
> -	count_pd = of_count_phandle_with_args(dev->of_node, "power-domains",
> -					      "#power-domain-cells");
> -	if (!count_pd)
> -		goto put_np;
> -
> -	if (count_pd > 1) {
> -		genpd_virt_devs = kcalloc(count, sizeof(*genpd_virt_devs),
> -					GFP_KERNEL);
> -		if (!genpd_virt_devs)
> -			goto put_np;
> -	}
> -
>  	required_opp_tables = kcalloc(count, sizeof(*required_opp_tables),
>  				      GFP_KERNEL);
> -	if (!required_opp_tables) {
> -		kfree(genpd_virt_devs);
> +	if (!required_opp_tables)
>  		goto put_np;
> -	}
>  
> -	opp_table->genpd_virt_devs = genpd_virt_devs;
>  	opp_table->required_opp_tables = required_opp_tables;
>  	opp_table->required_opp_count = count;
>  
> -- 
> 2.21.0.rc0.269.g1a574e7a288b
> 

Tested-by: Niklas Cassel <niklas.cassel@...aro.org>