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

From: Viresh Kumar <viresh.kumar@linaro.org>
To: Kamil Konieczny <k.konieczny@partner.samsung.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Chanwoo Choi <cw00.choi@samsung.com>,
	Krzysztof Kozlowski <krzk@kernel.org>,
	Kukjin Kim <kgene@kernel.org>,
	Kyungmin Park <kyungmin.park@samsung.com>,
	Mark Rutland <mark.rutland@arm.com>,
	MyungJoo Ham <myungjoo.ham@samsung.com>,
	Nishanth Menon <nm@ti.com>, Rob Herring <robh+dt@kernel.org>,
	Stephen Boyd <sboyd@kernel.org>,
	Viresh Kumar <vireshk@kernel.org>,
	devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
	linux-samsung-soc@vger.kernel.org
Subject: Re: [PATCH v2 1/4] opp: core: add regulators enable and disable
Date: Tue, 16 Jul 2019 15:35:39 +0530	[thread overview]
Message-ID: <20190716100539.4uqelbxqz7bmtmea@vireshk-i7> (raw)
In-Reply-To: <20190715120416.3561-2-k.konieczny@partner.samsung.com>

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@partner.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