linux-kernel - Re: [PATCH 12/13] regulator: add pm8008 pmic regulator driver

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Date: Tue, 7 May 2024 17:44:57 +0200
From: Johan Hovold <johan@...nel.org>
To: Andy Shevchenko <andy.shevchenko@...il.com>
Cc: Johan Hovold <johan+linaro@...nel.org>, Lee Jones <lee@...nel.org>,
	Mark Brown <broonie@...nel.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	Bjorn Andersson <andersson@...nel.org>,
	Konrad Dybcio <konrad.dybcio@...aro.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Liam Girdwood <lgirdwood@...il.com>,
	Das Srinagesh <quic_gurus@...cinc.com>,
	Satya Priya <quic_c_skakit@...cinc.com>,
	Stephen Boyd <swboyd@...omium.org>, linux-arm-msm@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-gpio@...r.kernel.org
Subject: Re: [PATCH 12/13] regulator: add pm8008 pmic regulator driver

On Mon, May 06, 2024 at 10:09:50PM +0300, Andy Shevchenko wrote:
> Mon, May 06, 2024 at 05:08:29PM +0200, Johan Hovold kirjoitti:
> > From: Satya Priya <quic_c_skakit@...cinc.com>
> > 
> > Qualcomm Technologies, Inc. PM8008 is an I2C-controlled PMIC containing
> > seven LDO regulators. Add a PM8008 regulator driver to support PMIC
> > regulator management via the regulator framework.
> > 
> > Note that this driver, originally submitted by Satya Priya [1], has been
> > reworked to match the new devicetree binding which no longer describes
> > each regulator as a separate device.

> > [1] https://lore.kernel.org/r/1655200111-18357-8-git-send-email-quic_c_skakit@quicinc.com
> 
> Make it Link: tag?
> 
> Link: URL [1]

Sure.

> > [ johan: rework probe to match new binding, amend commit message and
> >          Kconfig entry]
> 
> Wouldn't be better on one line?

Now you're really nit picking. ;) I think I prefer to stay within 72
columns.

> + array_size.h
> + bits.h

Ok.

> > +#include <linux/device.h>
> 
> > +#include <linux/kernel.h>
> 
> What is this header for?

Probably the ones that are not explicitly included.

> + math.h
> 
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/regmap.h>
> > +#include <linux/regulator/driver.h>
> 
> + asm/byteorder.h

Ok, thanks.

> > +static int pm8008_regulator_get_voltage(struct regulator_dev *rdev)
> > +{
> > +	struct pm8008_regulator *pm8008_reg = rdev_get_drvdata(rdev);
> > +	__le16 mV;
> > +	int uV;
> > +
> > +	regmap_bulk_read(pm8008_reg->regmap,
> > +			LDO_VSET_LB_REG(pm8008_reg->base), (void *)&mV, 2);
> 
> Why casting?

I tried not change things in the v15 from Qualcomm that I based this
on. I couldn't help cleaning up a few things in probe, which I was
touching anyway, but I left it there.

I'll drop the unnecessary cast.

> > +	uV = le16_to_cpu(mV) * 1000;
> > +	return (uV - pm8008_reg->rdesc.min_uV) / pm8008_reg->rdesc.uV_step;
> > +}
> > +
> > +static inline int pm8008_write_voltage(struct pm8008_regulator *pm8008_reg,
> > +							int mV)
> > +{
> > +	__le16 vset_raw;
> > +
> > +	vset_raw = cpu_to_le16(mV);
> 
> Can be joined to a single line.

Sure.

> > +	return regmap_bulk_write(pm8008_reg->regmap,
> > +			LDO_VSET_LB_REG(pm8008_reg->base),
> > +			(const void *)&vset_raw, sizeof(vset_raw));
> 
> Why casting?

Same answer as above. Will drop.

> > +}
> 
> ...
> 
> > +static int pm8008_regulator_set_voltage(struct regulator_dev *rdev,
> > +					unsigned int selector)
> > +{
> > +	struct pm8008_regulator *pm8008_reg = rdev_get_drvdata(rdev);
> > +	int rc, mV;
> > +
> > +	rc = regulator_list_voltage_linear_range(rdev, selector);
> > +	if (rc < 0)
> > +		return rc;
> > +
> > +	/* voltage control register is set with voltage in millivolts */
> > +	mV = DIV_ROUND_UP(rc, 1000);
> 
> > +	rc = pm8008_write_voltage(pm8008_reg, mV);
> > +	if (rc < 0)
> > +		return rc;
> > +
> > +	return 0;
> 
> 	return pm8008_write_voltage(pm8008_reg, mV);

Possibly, but I tend to prefer explicit error paths.

> > +}
> 
> > +
> > +	regmap = dev_get_regmap(dev->parent, "secondary");
> > +	if (!regmap)
> > +		return -EINVAL;
> > +
> > +	for (i = 0; i < ARRAY_SIZE(reg_data); i++) {
> > +		pm8008_reg = devm_kzalloc(dev, sizeof(*pm8008_reg), GFP_KERNEL);
> > +		if (!pm8008_reg)
> > +			return -ENOMEM;
> > +
> > +		pm8008_reg->regmap = regmap;
> > +		pm8008_reg->base = reg_data[i].base;
> > +
> > +		/* get slew rate */
> > +		rc = regmap_bulk_read(pm8008_reg->regmap,
> > +				LDO_STEPPER_CTL_REG(pm8008_reg->base), &val, 1);
> > +		if (rc < 0) {
> > +			dev_err(dev, "failed to read step rate: %d\n", rc);
> > +			return rc;
> 
> 			return dev_err_probe(...);

Nah, regmap won't trigger a probe deferral.

> > +static struct platform_driver pm8008_regulator_driver = {
> > +	.driver	= {
> > +		.name = "qcom-pm8008-regulator",
> > +	},
> > +	.probe = pm8008_regulator_probe,
> > +};
> 
> > +
> 
> Unneeded blank line.

I noticed that one too, but such things are up the author to decide.

> > +module_platform_driver(pm8008_regulator_driver);
> 
> ...
> 
> > +MODULE_ALIAS("platform:qcom-pm8008-regulator");
> 
> Use ID table instead.

No, the driver is not using an id-table for matching so the alias is
needed for module auto-loading.

Johan