linux-kernel - Re: [PATCH v4 2/2] regulator: add device tree support for max8997

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Message-id: <4F734460.4060605@samsung.com>
Date:	Wed, 28 Mar 2012 19:03:28 +0200
From:	Karol Lewandowski <k.lewandowsk@...sung.com>
To:	Thomas Abraham <thomas.abraham@...aro.org>
Cc:	linux-kernel@...r.kernel.org, devicetree-discuss@...ts.ozlabs.org,
	rob.herring@...xeda.com, grant.likely@...retlab.ca,
	kgene.kim@...sung.com, broonie@...nsource.wolfsonmicro.com,
	myungjoo.ham@...sung.com, kyungmin.park@...sung.com,
	linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org, patches@...aro.org,
	Rajendra Nayak <rnayak@...com>
Subject: Re: [PATCH v4 2/2] regulator: add device tree support for max8997

On 24.03.2012 10:49, Thomas Abraham wrote:

Hi Thomas!

> Add device tree based discovery support for max8997.
... 
> +Regulators: The regulators of max8997 that have to be instantiated should be
> +included in a sub-node named 'regulators'. Regulator nodes included in this
> +sub-node should be of the format as below. Note: The 'n' in LDOn and BUCKn
> +represents the LDO or BUCK number as per the datasheet of max8997.
> +
> +    For LDO's:
> +		LDOn {
> +			standard regulator bindings here
> +		};
> +
> +    For BUCK's:
> +		BUCKn {
> +			standard regulator bindings here
> +		};
> +


Small note - driver supports[1] configuring following regulators by
using respective DT node names:

 - EN32KHz_AP
 - EN32KHz_CP
 - ENVICHG
 - ESAFEOUT1
 - ESAFEOUT2
 - CHARGER
 - CHARGER_CV
 - CHARGER_TOPOFF

I wonder if these should be mentioned in documentation too.

[1] These are used in e.g. mach-nuri.c

> diff --git a/drivers/regulator/max8997.c b/drivers/regulator/max8997.c> index 9657929..dce8aaf 100644

> --- a/drivers/regulator/max8997.c
> +++ b/drivers/regulator/max8997.c
..
> +static int max8997_pmic_dt_parse_pdata(struct max8997_dev *iodev,
> +					struct max8997_platform_data *pdata)
> +{
> +	struct device_node *pmic_np, *regulators_np, *reg_np;
> +	struct max8997_regulator_data *rdata;
> +	unsigned int i, dvs_voltage_nr = 1, ret;
> +
> +	pmic_np = iodev->dev->of_node;
> +	if (!pmic_np) {
> +		dev_err(iodev->dev, "could not find pmic sub-node\n");
> +		return -ENODEV;
> +	}
> +
> +	regulators_np = of_find_node_by_name(pmic_np, "regulators");
> +	if (!regulators_np) {
> +		dev_err(iodev->dev, "could not find regulators sub-node\n");
> +		return -EINVAL;
> +	}
> +
> +	/* count the number of regulators to be supported in pmic */
> +	pdata->num_regulators = 0;
> +	for_each_child_of_node(regulators_np, reg_np)
> +		pdata->num_regulators++;
> +
> +	rdata = devm_kzalloc(iodev->dev, sizeof(*rdata) *
> +				pdata->num_regulators, GFP_KERNEL);
> +	if (!rdata) {
> +		dev_err(iodev->dev, "could not allocate memory for "
> +						"regulator data\n");
> +		return -ENOMEM;
> +	}

> +	pdata->regulators = rdata;

> +	for_each_child_of_node(regulators_np, reg_np) {
> +		for (i = 0; i < ARRAY_SIZE(regulators); i++)
> +			if (!of_node_cmp(reg_np->name, regulators[i].name))
> +				break;
> +		rdata->id = i;


rdata->id will be equal to ARRAY_SIZE(regulators) when one adds DT node
name (below "regulators") which is different from what can be found in
regulators[] table.

On my test machine this results in hard lockup - possibly because
something tries to access regulators[ARRAY_SIZE(regulators)]
later on.

Following patch fixes this on my machine (using DTS with misspelled LDO1 for LDx1):

diff --git a/drivers/regulator/max8997.c b/drivers/regulator/max8997.c
index dce8aaf..c20fd72 100644
--- a/drivers/regulator/max8997.c
+++ b/drivers/regulator/max8997.c
@@ -1011,6 +1011,13 @@ static int max8997_pmic_dt_parse_pdata(struct max8997_dev *iodev,
                for (i = 0; i < ARRAY_SIZE(regulators); i++)
                        if (!of_node_cmp(reg_np->name, regulators[i].name))
                                break;
+
+               if (i == ARRAY_SIZE(regulators)) {
+                       dev_warn(iodev->dev, "don't know how to configure regulator %s\n",
+                                reg_np->name);
+                       continue;
+               }
+
                rdata->id = i;
                rdata->initdata = of_get_regulator_init_data(
                                                iodev->dev, reg_np);


Regards,
-- 
Karol Lewandowski | Samsung Poland R&D Center | Linux/Platform
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