linux-kernel - Re: [PATCH V4 06/10] PM / OPP: Add infrastructure to manage multiple regulators

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Message-ID: <20161129005512.GQ6095@codeaurora.org>
Date:   Mon, 28 Nov 2016 16:55:12 -0800
From:   Stephen Boyd <sboyd@...eaurora.org>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Rafael Wysocki <rjw@...ysocki.net>, nm@...com,
        Viresh Kumar <vireshk@...nel.org>,
        linaro-kernel@...ts.linaro.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>, robh@...nel.org,
        d-gerlach@...com, broonie@...nel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH V4 06/10] PM / OPP: Add infrastructure to manage multiple
 regulators

On 11/24, Viresh Kumar wrote:
> diff --git a/drivers/base/power/opp/core.c b/drivers/base/power/opp/core.c
> index 37fad2eb0f47..2d5c726c920f 100644
> --- a/drivers/base/power/opp/core.c
> +++ b/drivers/base/power/opp/core.c
> @@ -235,21 +240,41 @@ unsigned long dev_pm_opp_get_max_volt_latency(struct device *dev)
>  		return 0;
>  	}
>  
> -	reg = opp_table->regulator;
> -	if (IS_ERR(reg)) {
> +	count = opp_table->regulator_count;
> +
> +	if (!count) {
>  		/* Regulator may not be required for device */
>  		rcu_read_unlock();
>  		return 0;
>  	}
>  
> -	list_for_each_entry_rcu(opp, &opp_table->opp_list, node) {
> -		if (!opp->available)
> -			continue;
> +	size = count * sizeof(*regulators);
> +	regulators = kmemdup(opp_table->regulators, size, GFP_KERNEL);

Again, can't allocate with sleeping calls under RCU read lock as
it may have disabled preemption.

> +	if (!regulators) {
> +		rcu_read_unlock();
> +		return 0;
> +	}
> +
> +	uV = kmalloc_array(count, sizeof(*uV), GFP_KERNEL);
> +	if (!uV) {
> +		kfree(regulators);
> +		rcu_read_unlock();
> +		return 0;
> +	}
>  
> -		if (opp->supply.u_volt_min < min_uV)
> -			min_uV = opp->supply.u_volt_min;
> -		if (opp->supply.u_volt_max > max_uV)
> -			max_uV = opp->supply.u_volt_max;
> +	for (i = 0; i < count; i++) {
> +		uV[i].min = ~0;
> +		uV[i].max = 0;
> +
> +		list_for_each_entry_rcu(opp, &opp_table->opp_list, node) {
> +			if (!opp->available)
> +				continue;
> +
> +			if (opp->supplies[i].u_volt_min < uV[i].min)
> +				uV[i].min = opp->supplies[i].u_volt_min;
> +			if (opp->supplies[i].u_volt_max > uV[i].max)
> +				uV[i].max = opp->supplies[i].u_volt_max;
> +		}
>  	}
>  
>  	rcu_read_unlock();
> @@ -924,35 +960,50 @@ struct dev_pm_opp *_allocate_opp(struct device *dev,
>  				 struct opp_table **opp_table)
>  {
>  	struct dev_pm_opp *opp;
> +	int count, supply_size;
> +	struct opp_table *table;
>  
> -	/* allocate new OPP node */
> -	opp = kzalloc(sizeof(*opp), GFP_KERNEL);
> -	if (!opp)
> +	table = _add_opp_table(dev);
> +	if (!table)
>  		return NULL;
>  
> -	INIT_LIST_HEAD(&opp->node);
> +	/* Allocate space for at least one supply */
> +	count = table->regulator_count ? table->regulator_count : 1;
> +	supply_size = sizeof(*opp->supplies) * count;
>  
> -	*opp_table = _add_opp_table(dev);
> -	if (!*opp_table) {
> -		kfree(opp);
> +	/* allocate new OPP node + and supplies structures */

s/+//

> +	opp = kzalloc(sizeof(*opp) + supply_size, GFP_KERNEL);
> +	if (!opp) {
> +		kfree(table);
>  		return NULL;
>  	}
>  
-- 
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