linux-kernel - Re: [PATCH v3 4/5] regulator: max14577: Add regulator driver for Maxim 14577

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Message-ID: <20131122101551.GJ23067@lee--X1>
Date:	Fri, 22 Nov 2013 10:15:51 +0000
From:	Lee Jones <lee.jones@...aro.org>
To:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
Cc:	MyungJoo Ham <myungjoo.ham@...sung.com>,
	Chanwoo Choi <cw00.choi@...sung.com>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Anton Vorontsov <anton@...msg.org>,
	David Woodhouse <dwmw2@...radead.org>,
	Liam Girdwood <lgirdwood@...il.com>,
	Mark Brown <broonie@...nel.org>,
	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <rob.herring@...xeda.com>,
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	Pawel Moll <pawel.moll@....com>,
	Stephen Warren <swarren@...dotorg.org>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Rob Landley <rob@...dley.net>, linux-doc@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Kyungmin Park <kyungmin.park@...sung.com>
Subject: Re: [PATCH v3 4/5] regulator: max14577: Add regulator driver for
 Maxim 14577

On Fri, 22 Nov 2013, Krzysztof Kozlowski wrote:

> MAX14577 chip is a multi-function device which includes MUIC,
> charger and voltage regulator. The driver is located in drivers/mfd.
> 
> This patch adds regulator driver for MAX14577 chip. There are two
> regulators in this chip:
> 1. Safeout LDO with constant voltage output of 4.9V. It can be only
>    enabled or disabled.
> 2. Current regulator for the charger. It provides current from 90mA up
>    to 950mA.
> Driver supports Device Tree.
> 
> Signed-off-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@...sung.com>
> ---
>  drivers/regulator/Kconfig    |    7 ++
>  drivers/regulator/Makefile   |    1 +
>  drivers/regulator/max14577.c |  272 ++++++++++++++++++++++++++++++++++++++++++
>  include/linux/mfd/max14577.h |    1 -
>  4 files changed, 280 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/regulator/max14577.c

<snip>

> +#ifdef CONFIG_OF
> +static int max14577_regulator_dt_parse_pdata(struct platform_device *pdev,
> +					struct max14577_platform_data *pdata)
> +{
> +	struct max14577 *max14577 = dev_get_drvdata(pdev->dev.parent);
> +	struct device_node *np;
> +	struct max14577_regulator_platform_data *reg_pdata;
> +	struct of_regulator_match rmatch;
> +	int i, ret;
> +
> +	np = of_get_child_by_name(max14577->dev->of_node, "regulators");
> +	if (!np)
> +		return -EINVAL;

No need to do this. If instead you use a compatible string and set
it's MFD cell's .of_compatible property, the MFD core will set
pdev->dev.of_node for you.

> +	reg_pdata = devm_kzalloc(&pdev->dev, sizeof(*reg_pdata) *
> +			     ARRAY_SIZE(supported_regulators), GFP_KERNEL);
> +	if (!reg_pdata)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < ARRAY_SIZE(supported_regulators); i++) {
> +		rmatch.name = supported_regulators[i].name;
> +		ret = of_regulator_match(&pdev->dev, np, &rmatch, 1);
> +		if (ret != 1)
> +			continue;
> +		dev_dbg(&pdev->dev, "Found regulator %d/%s\n",
> +				supported_regulators[i].id,
> +				supported_regulators[i].name);
> +		reg_pdata[i].id = supported_regulators[i].id;
> +		reg_pdata[i].initdata = rmatch.init_data;
> +		reg_pdata[i].of_node = rmatch.of_node;
> +	}
> +
> +	pdata->regulators = reg_pdata;
> +
> +	return 0;
> +}
> +#else
> +static int max14577_regulator_dt_parse_pdata(struct platform_device *pdev,
> +					struct max14577_platform_data *pdata)
> +{
> +	return 0;
> +}
> +#endif

No need for this either. Just check for the device's of_node.

> +static int max14577_regulator_probe(struct platform_device *pdev)
> +{
> +	struct max14577 *max14577 = dev_get_drvdata(pdev->dev.parent);
> +	struct max14577_platform_data *pdata = dev_get_platdata(max14577->dev);
> +	int i, size;
> +	struct regulator_config config = {};
> +	struct regulator_dev **regulators;
> +
> +	if (!pdata) {
> +		/* Parent must provide pdata */
> +		dev_err(&pdev->dev, "No MFD driver platform data found.\n");
> +		return -ENODEV;
> +	}
> +
> +	if (max14577->dev->of_node) {
> +		int ret = max14577_regulator_dt_parse_pdata(pdev, pdata);

This will overwrite pdata which is wrong.

pdata should always take precedence over DT.

<snip>

> +	for (i = 0; i < ARRAY_SIZE(supported_regulators); i++) {
> +		/*
> +		 * Index of supported_regulators[] is also the id and must
> +		 * match index of pdata->regulators[].
> +		 */
> +		config.init_data = pdata->regulators[i].initdata;
> +		config.of_node = pdata->regulators[i].of_node;

I still thing this is superfluous. Why don't you run though the nodes
here instead of doing it in MFD and passing this stuff through?

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
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