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

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Date:   Tue, 16 Jul 2019 15:35:39 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Kamil Konieczny <k.konieczny@...tner.samsung.com>
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 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.

> +
>  		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

-- 
viresh