Re: [PATCH v6 3/4] iio: add MEMSensing MSA311 3-axis accelerometer driver

From: Andy Shevchenko
Date: Fri Aug 19 2022 - 04:42:45 EST


On Tue, Aug 16, 2022 at 10:18 PM Dmitry Rokosov
<DDRokosov@xxxxxxxxxxxxxx> wrote:
>
> 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.
>
> 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

> Spec: https://cdn-shop.adafruit.com/product-files/5309/MSA311-V1.1-ENG.pdf

Have you ever seen such a tag?
We have the Datasheet that is more or less established for this kind of links.

The comments below are not a big deal, though.

...

> +static const struct iio_decimal_fract msa311_fs_table[] = {
> + {0, 9580}, {0, 19160}, {0, 38320}, {0, 76641}

I would still keep the trailing comma for better consistency with a style.

> +};

...

> +static const struct iio_decimal_fract msa311_odr_table[] = {
> + {1, 0}, {1, 950000}, {3, 900000}, {7, 810000}, {15, 630000},
> + {31, 250000}, {62, 500000}, {125, 0}, {250, 0}, {500, 0}, {1000, 0}

Ditto.

> +};

...

> +struct msa311_priv {
> + struct regmap *regs;
> + struct regmap_field *fields[F_MAX_FIELDS];
> +
> + struct device *dev;
> + struct mutex lock;

> + char chip_name[10];

Why limit it to 10? You may use devm_kasprintf()

> + struct iio_trigger *new_data_trig;
> + struct regulator *vdd;
> +};

...

> +static inline int msa311_set_odr(struct msa311_priv *msa311, unsigned int odr)

Why inline?

> +{
> + struct device *dev = msa311->dev;
> + unsigned int pwr_mode;

> + bool good_odr = false;

Can it be split to see the assignments together below?

> + int err;
> +
> + err = regmap_field_read(msa311->fields[F_PWR_MODE], &pwr_mode);
> + if (err)
> + return err;
> +
> + /* Filter bad ODR values */
> + if (pwr_mode == MSA311_PWR_MODE_NORMAL)
> + good_odr = (odr > MSA311_ODR_1_95_HZ);

else
good_odr = false;

> + if (!good_odr) {
> + dev_err(dev,
> + "can't set odr %u.%06uHz, not available in %s mode\n",
> + msa311_odr_table[odr].integral,
> + msa311_odr_table[odr].microfract,
> + msa311_pwr_modes[pwr_mode]);
> + return -EINVAL;
> + }
> +
> + return regmap_field_write(msa311->fields[F_ODR], odr);
> +}

...

> + if (wait_ms < unintr_thresh_ms)
> + usleep_range(wait_ms * USEC_PER_MSEC,
> + unintr_thresh_ms * USEC_PER_MSEC);
> + else
> + return msleep_interruptible(wait_ms) ? -EINTR : 0;

Can be refactored to simple

else if (msleep...)
return -EINTR;

Same amount of LoCs, but more readable.

> + return 0;

...

> +err:

We usually name labels after what they are doing, I don't see any
error here, but notify done. Hence,

out_notify_done:

> + iio_trigger_notify_done(indio_dev->trig);
> +
> + return IRQ_HANDLED;

...

> + used = scnprintf(msa311->chip_name, sizeof(msa311->chip_name),
> + "msa311-%hhx", partid);

How 'used' is being used?

> + return 0;
> +}

...

> + const char zero_bulk[2] = {0};

0 is not needed, '{ }' will work.

...

> + /*
> + * Register powerdown deferred callback which suspends the chip
> + * after module unloaded.
> + *
> + * MSA311 should be in SUSPEND mode in the two cases:
> + * 1) When driver is loaded, but we do not have any data or
> + * configuration requests to it (we are solving it using
> + * autosuspend feature).
> + * 2) When driver is unloaded and device is not used (devm action is
> + * used in this case).
> + */

...

> +static struct i2c_driver msa311_driver = {
> + .driver = {
> + .name = "msa311",

> + .owner = THIS_MODULE,

Redundant.

> + .of_match_table = msa311_of_match,
> + .pm = pm_ptr(&msa311_pm_ops),
> + },
> + .probe_new = msa311_probe,
> + .id_table = msa311_i2c_id,
> +};

--
With Best Regards,
Andy Shevchenko