linux-kernel - Re: [PATCH v4 2/3] iio: add MEMSensing MSA311 3-axis accelerometer driver

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Date:   Wed, 3 Aug 2022 18:39:49 +0000
From:   Dmitry Rokosov <DDRokosov@...rdevices.ru>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>
CC:     "andy.shevchenko@...il.com" <andy.shevchenko@...il.com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "jic23@...nel.org" <jic23@...nel.org>,
        kernel <kernel@...rdevices.ru>,
        "lars@...afoo.de" <lars@...afoo.de>,
        "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "stano.jakubek@...il.com" <stano.jakubek@...il.com>,
        "stephan@...hold.net" <stephan@...hold.net>
Subject: Re: [PATCH v4 2/3] iio: add MEMSensing MSA311 3-axis accelerometer
 driver

Hello Christophe,

Thank you for quick review

On Wed, Aug 03, 2022 at 08:11:05PM +0200, Christophe JAILLET wrote:
> Le 03/08/2022 à 15:11, Dmitry Rokosov a écrit :
> > MSA311 is a tri-axial, low-g accelerometer with I2C digital output for
> > sensitivity consumer applications. It has dynamic user-selectable full
> > scales range of +-2g/+-4g/+-8g/+-16g and allows acceleration measurements
> > with output data rates from 1Hz to 1000Hz.
> > 
> > Spec: https://cdn-shop.adafruit.com/product-files/5309/MSA311-V1.1-ENG.pdf
> > 
> > This driver supports following MSA311 features:
> >      - IIO interface
> >      - Different power modes: NORMAL and SUSPEND (using pm_runtime)
> >      - ODR (Output Data Rate) selection
> >      - Scale and samp_freq selection
> >      - IIO triggered buffer, IIO reg access
> >      - NEW_DATA interrupt + trigger
> > 
> > Below features to be done:
> >      - Motion Events: ACTIVE, TAP, ORIENT, FREEFALL
> >      - Low Power mode
> > 
> > Signed-off-by: Dmitry Rokosov <ddrokosov-i4r8oA+eLlH99rHkP+FxIw@...lic.gmane.org>
> > ---
> >   MAINTAINERS                |    6 +
> >   drivers/iio/accel/Kconfig  |   13 +
> >   drivers/iio/accel/Makefile |    2 +
> >   drivers/iio/accel/msa311.c | 1323 ++++++++++++++++++++++++++++++++++++
> >   4 files changed, 1344 insertions(+)
> >   create mode 100644 drivers/iio/accel/msa311.c
> > 
> 
> Hi,
> a few nits below.
> 
> [...]
> 
> > +static int msa311_check_partid(struct msa311_priv *msa311)
> > +{
> > +	struct device *dev = msa311->dev;
> > +	unsigned int partid;
> > +	int err;
> > +
> > +	err = regmap_read(msa311->regs, MSA311_PARTID_REG, &partid);
> > +	if (err)
> > +		return dev_err_probe(dev, err,
> > +				     "failed to read partid (%d)\n", err);
> 
> No need for "(%d)" and err.
> 

Do you mean for all dev_err() calls? I think sometimes it's helpful to
know the actual error value got from external API, isn't? Could you please
explain your point if possible?

> > +
> > +	if (partid == MSA311_WHO_AM_I)
> > +		dev_dbg(dev, "found MSA311 compatible chip[%#x]\n", partid);
> > +	else
> > +		dev_warn(dev, "invalid partid (%#x), expected (%#x)\n",
> > +			 partid, MSA311_WHO_AM_I);
> > +
> > +	return 0;
> > +}
> 
> [...]
> 
> > +static int msa311_probe(struct i2c_client *i2c)
> > +{
> > +	struct device *dev = &i2c->dev;
> > +	struct msa311_priv *msa311;
> > +	struct iio_dev *indio_dev;
> > +	int err;
> > +
> > +	indio_dev = devm_iio_device_alloc(dev, sizeof(*msa311));
> > +	if (!indio_dev)
> > +		return dev_err_probe(dev, -ENOMEM,
> > +				     "iio device allocation failed\n");
> > +
> > +	msa311 = iio_priv(indio_dev);
> > +	msa311->dev = dev;
> > +	i2c_set_clientdata(i2c, indio_dev);
> > +
> > +	err = msa311_regmap_init(msa311);
> > +	if (err)
> > +		return err;
> > +
> > +	mutex_init(&msa311->lock);
> > +
> > +	msa311->vdd = devm_regulator_get_optional(dev, "vdd");
> > +	if (IS_ERR(msa311->vdd)) {
> > +		err = PTR_ERR(msa311->vdd);
> > +		if (err == -ENODEV)
> > +			msa311->vdd = NULL;
> > +		else
> > +			return dev_err_probe(dev, PTR_ERR(msa311->vdd),
> > +					     "cannot get vdd supply\n");
> > +	}
> > +
> > +	if (msa311->vdd) {
> > +		err = regulator_enable(msa311->vdd);
> > +		if (err)
> > +			return dev_err_probe(dev, err,
> > +					     "cannot enable vdd supply\n");
> > +
> > +		err = devm_add_action_or_reset(dev, msa311_vdd_disable,
> > +					       msa311->vdd);
> > +		if (err) {
> > +			regulator_disable(msa311->vdd);
> 
> Double regulator_disable(), because of the _or_reset()?
> 

Yep. If devm_add_action_or_reset() returns an error, we will not
call regulator_disable() by devm subsystem. It means, we have to
call it directly.

> > +			return dev_err_probe(dev, err,
> > +					     "cannot add vdd disable action\n");
> > +		}
> > +	}
> > +
> > +	err = msa311_check_partid(msa311);
> > +	if (err)
> > +		return err;
> > +
> > +	err = msa311_soft_reset(msa311);
> > +	if (err)
> > +		return err;
> > +
> > +	err = msa311_set_pwr_mode(msa311, MSA311_PWR_MODE_NORMAL);
> > +	if (err)
> > +		return dev_err_probe(dev, err,
> > +				     "failed to power on device (%d)\n", err);
> 
> No need for "(%d)" and err

Asked for the clarification above.

> 
> CJ

-- 
Thank you,
Dmitry