Re: [PATCH v3 4/4] iio: magnetometer: ak8975: Add gpio reset support

Jonathan Albrieux
2020-05-19T14:10:47Z

On Tue, May 19, 2020 at 03:25:12PM +0200, Stephan Gerhold wrote:
> On Tue, May 19, 2020 at 02:43:54PM +0200, Jonathan Albrieux wrote:
> > According to AK09911 datasheet, if reset gpio is provided then
> > deassert reset on ak8975_power_on() and assert reset on ak8975_power_off().
> >
> > Without reset's deassertion during ak8975_power_on(), driver's probe fails
> > on ak8975_who_i_am while() checking for device identity for AK09911 chip.
> >
> > AK09911 has an active low reset gpio to handle register's reset.
> > AK09911 datasheed says that, if not used, reset pin should be connected
>
> Another minor typo: datasheed -> datasheet
>
> In any case, FWIW:
> Reviewed-by: Stephan Gerhold <stephan@gerhold.net>
>
> > to VID. This patch emulates this situation.
> >
> > Signed-off-by: Jonathan Albrieux <jonathan.albrieux@gmail.com>
> > ---
> > drivers/iio/magnetometer/ak8975.c | 18 ++++++++++++++++++
> > 1 file changed, 18 insertions(+)
> >
> > diff --git a/drivers/iio/magnetometer/ak8975.c b/drivers/iio/magnetometer/ak8975.c
> > index fd368455cd7b..a23422aad97d 100644
> > --- a/drivers/iio/magnetometer/ak8975.c
> > +++ b/drivers/iio/magnetometer/ak8975.c
> > @@ -358,6 +358,7 @@ struct ak8975_data {
> > u8 asa[3];
> > long raw_to_gauss[3];
> > struct gpio_desc *eoc_gpiod;
> > + struct gpio_desc *reset_gpiod;
> > int eoc_irq;
> > wait_queue_head_t data_ready_queue;
> > unsigned long flags;
> > @@ -384,6 +385,9 @@ static int ak8975_power_on(const struct ak8975_data *data)
> > "Failed to enable specified Vid supply\n");
> > return ret;
> > }
> > +
> > + gpiod_set_value_cansleep(data->reset_gpiod, 0);
> > +
> > /*
> > * According to the datasheet the power supply rise time is 200us
> > * and the minimum wait time before mode setting is 100us, in
> > @@ -396,6 +400,8 @@ static int ak8975_power_on(const struct ak8975_data *data)
> > /* Disable attached power regulator if any. */
> > static void ak8975_power_off(const struct ak8975_data *data)
> > {
> > + gpiod_set_value_cansleep(data->reset_gpiod, 1);
> > +
> > regulator_disable(data->vid);
> > regulator_disable(data->vdd);
> > }
> > @@ -839,6 +845,7 @@ static int ak8975_probe(struct i2c_client *client,
> > struct ak8975_data *data;
> > struct iio_dev *indio_dev;
> > struct gpio_desc *eoc_gpiod;
> > + struct gpio_desc *reset_gpiod;
> > const void *match;
> > unsigned int i;
> > int err;
> > @@ -856,6 +863,16 @@ static int ak8975_probe(struct i2c_client *client,
> > if (eoc_gpiod)
> > gpiod_set_consumer_name(eoc_gpiod, "ak_8975");
> >
> > + /*
> > + * According to AK09911 datasheet, if reset GPIO is provided then
> > + * deassert reset on ak8975_power_on() and assert reset on
> > + * ak8975_power_off().
> > + */
> > + reset_gpiod = devm_gpiod_get_optional(&client->dev,
> > + "reset", GPIOD_OUT_HIGH);
> > + if (IS_ERR(reset_gpiod))
> > + return PTR_ERR(reset_gpiod);
> > +
> > /* Register with IIO */
> > indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
> > if (indio_dev == NULL)
> > @@ -866,6 +883,7 @@ static int ak8975_probe(struct i2c_client *client,
> >
> > data->client = client;
> > data->eoc_gpiod = eoc_gpiod;
> > + data->reset_gpiod = reset_gpiod;
> > data->eoc_irq = 0;
> >
> > err = iio_read_mount_matrix(&client->dev, "mount-matrix", &data->orientation);
> > --
> > 2.17.1

Thank you, will fix that typo too,

Best regards,
Jonathan Albrieux