On Fri, May 26, 2017 at 02:35:16PM +0800, Guodong Xu wrote:

Overall this driver needs quite a lot of modernization, it's at least a
couple of years out of date in how it's using the framework - there's
barely any use of helpers.  It does look like it should be fairly easy
to get it up to date though, it's mostly going to be a case of deleting
code that's reimplementing helpers rather than anything else.

+/*
+ * struct hi6421c530_regulator_pdata - Hi6421V530 regulator data
+ * of platform device.
+ * @lock: mutex to serialize regulator enable
+ */
+struct hi6421v530_regulator_pdata {
+	struct mutex lock;
+};

This isn't platform data so it probably shouldn't be called pdata.  I
also can't tell what the lock is protecting, every use seems to be a
call to regmap_update_bits() which is atomic anyway - could we just drop
the whole thing?

+static int hi6421v530_regulator_enable(struct regulator_dev *rdev)
+{
+	struct hi6421v530_regulator_pdata *pdata;
+	int ret = 0;
+
+	pdata = dev_get_drvdata(rdev->dev.parent);
+	mutex_lock(&pdata->lock);
+
+	ret = regmap_update_bits(rdev->regmap, rdev->desc->enable_reg,
+			rdev->desc->enable_mask,
+			1 << (ffs(rdev->desc->enable_mask) - 1));
+
+	mutex_unlock(&pdata->lock);
+	return ret;
+}

This looks like it should be able to use the regmap helpers for all the
enable operations rather than open coding.  

+static int hi6421v530_regulator_set_voltage(struct regulator_dev *rdev,
+						unsigned int sel)
+{
+	struct hi6421v530_regulator_pdata *pdata;
+	int ret = 0;
+
+	pdata = dev_get_drvdata(rdev->dev.parent);
+	mutex_lock(&pdata->lock);
+
+	ret = regmap_update_bits(rdev->regmap, rdev->desc->vsel_reg,
+				rdev->desc->vsel_mask,
+				sel << (ffs(rdev->desc->vsel_mask) - 1));

Same for all the voltage operations :(

+	rdev->constraints->valid_modes_mask = info->mode_mask;
+	rdev->constraints->valid_ops_mask |=
+			REGULATOR_CHANGE_VOLTAGE | REGULATOR_CHANGE_MODE;

The driver should *never* modify constraints, it's up to the machine
integration to say what can be supported on a given board.

+	np = of_get_child_by_name(dev->parent->of_node, "regulators");
+	if (!np)
+		return -ENODEV;
+
+	ret = of_regulator_match(dev, np,
+				 hi6421v530_regulator_match,
+				 ARRAY_SIZE(hi6421v530_regulator_match));

Don't open code this, use of_match and regulators_node.
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