linux-kernel - Re: [PATCH v2 1/4] opp: core: add regulators enable and disable

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Date:   Wed, 17 Jul 2019 16:14:54 +0200
From:   Kamil Konieczny <k.konieczny@...tner.samsung.com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Kukjin Kim <kgene@...nel.org>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Mark Rutland <mark.rutland@....com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Nishanth Menon <nm@...com>, Rob Herring <robh+dt@...nel.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Viresh Kumar <vireshk@...nel.org>, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-samsung-soc@...r.kernel.org
Subject: Re: [PATCH v2 1/4] opp: core: add regulators enable and disable

On 16.07.2019 12:05, Viresh Kumar wrote:
> On 15-07-19, 14:04, Kamil Konieczny wrote:
>> Add enable regulators to dev_pm_opp_set_regulators() and disable
>> regulators to dev_pm_opp_put_regulators(). This prepares for
>> converting exynos-bus devfreq driver to use dev_pm_opp_set_rate().
>>
>> Signed-off-by: Kamil Konieczny <k.konieczny@...tner.samsung.com>
>> --
>> Changes in v2:
>>
>> - move regulator enable and disable into loop
>>
>> ---
>>  drivers/opp/core.c | 18 +++++++++++++++---
>>  1 file changed, 15 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
>> index 0e7703fe733f..069c5cf8827e 100644
>> --- a/drivers/opp/core.c
>> +++ b/drivers/opp/core.c
>> @@ -1570,6 +1570,10 @@ struct opp_table *dev_pm_opp_set_regulators(struct device *dev,
>>  			goto free_regulators;
>>  		}
>>  
>> +		ret = regulator_enable(reg);
>> +		if (ret < 0)
>> +			goto disable;
> 
> The name of this label is logically incorrect because we won't disable
> the regulator from there but put it. Over that, I would rather prefer
> to remove the label and add regulator_put() here itself.

I will change this and following according to your suggestions and will send v3.

>> +
>>  		opp_table->regulators[i] = reg;
>>  	}
>>  
>> @@ -1582,9 +1586,15 @@ struct opp_table *dev_pm_opp_set_regulators(struct device *dev,
>>  
>>  	return opp_table;
>>  
>> +disable:
>> +	regulator_put(reg);
>> +	--i;
>> +
>>  free_regulators:
>> -	while (i != 0)
>> -		regulator_put(opp_table->regulators[--i]);
>> +	for (; i >= 0; --i) {
>> +		regulator_disable(opp_table->regulators[i]);
>> +		regulator_put(opp_table->regulators[i]);
> 
> This is incorrect as this will now try to put/disable the regulator
> which we failed to acquire. As --i happens only after the loop has run
> once. You can rather do:
> 
> 	while (i--) {
> 		regulator_disable(opp_table->regulators[i]);
> 		regulator_put(opp_table->regulators[i]);
>         }
> 
> 
>> +	}
>>  
>>  	kfree(opp_table->regulators);
>>  	opp_table->regulators = NULL;
>> @@ -1610,8 +1620,10 @@ void dev_pm_opp_put_regulators(struct opp_table *opp_table)
>>  	/* Make sure there are no concurrent readers while updating opp_table */
>>  	WARN_ON(!list_empty(&opp_table->opp_list));
>>  
>> -	for (i = opp_table->regulator_count - 1; i >= 0; i--)
>> +	for (i = opp_table->regulator_count - 1; i >= 0; i--) {
>> +		regulator_disable(opp_table->regulators[i]);
>>  		regulator_put(opp_table->regulators[i]);
>> +	}
>>  
>>  	_free_set_opp_data(opp_table);
>>  
>> -- 
>> 2.22.0
> 

-- 
Best regards,
Kamil Konieczny
Samsung R&D Institute Poland