linux-kernel - Re: [PATCH v3 2/7] iio: pressure: bmp280: Add support for bmp280 soft reset

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Message-ID: <20240828074905.GA4934@vamoiridPC>
Date: Wed, 28 Aug 2024 09:49:05 +0200
From: Vasileios Amoiridis <vassilisamir@...il.com>
To: Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc: vassilisamir@...il.com, 579lpy@...il.com, ak@...klinger.de,
	andriy.shevchenko@...ux.intel.com, ang.iglesiasg@...il.com,
	biju.das.jz@...renesas.com, conor+dt@...nel.org,
	devicetree@...r.kernel.org, javier.carrasco.cruz@...il.com,
	jic23@...nel.org, krzk+dt@...nel.org, lars@...afoo.de,
	linus.walleij@...aro.org, linux-iio@...r.kernel.org,
	linux-kernel@...r.kernel.org, robh@...nel.org,
	semen.protsenko@...aro.org
Subject: Re: [PATCH v3 2/7] iio: pressure: bmp280: Add support for bmp280
 soft reset

On Sun, Aug 25, 2024 at 09:04:16AM +0200, Christophe JAILLET wrote:
> Le 23/08/2024 à 20:17, Vasileios Amoiridis a écrit :
> > The BM(P/E)28x devices have an option for soft reset which is also
> > recommended by the Bosch Sensortech BME2 Sensor API to be used before the
> > initial configuration of the device.
> > 
> > Link: https://github.com/boschsensortec/BME280_SensorAPI/blob/bme280_v3.5.1/bme280.c#L429
> > Signed-off-by: Vasileios Amoiridis <vassilisamir-Re5JQEeQqe8AvxtiuMwx3w@...lic.gmane.org>
> > ---
> >   drivers/iio/pressure/bmp280-core.c | 26 ++++++++++++++++++++++++++
> >   drivers/iio/pressure/bmp280.h      |  3 +++
> >   2 files changed, 29 insertions(+)
> > 
> > diff --git a/drivers/iio/pressure/bmp280-core.c b/drivers/iio/pressure/bmp280-core.c
> > index c23515048081..e01c9369bd67 100644
> > --- a/drivers/iio/pressure/bmp280-core.c
> > +++ b/drivers/iio/pressure/bmp280-core.c
> > @@ -965,6 +965,30 @@ static const unsigned long bme280_avail_scan_masks[] = {
> >   	0
> >   };
> > +static int bmp280_preinit(struct bmp280_data *data)
> > +{
> > +	unsigned int reg;
> > +	int ret;
> > +
> > +	ret = regmap_write(data->regmap, BMP280_REG_RESET, BMP280_RST_SOFT_CMD);
> > +	if (ret)
> > +		return dev_err_probe(data->dev, ret,
> > +				     "Failed to reset device.\n");
> > +
> > +	usleep_range(data->start_up_time, data->start_up_time + 500);
> > +
> > +	ret = regmap_read(data->regmap, BMP280_REG_STATUS, &reg);
> > +	if (ret)
> > +		return dev_err_probe(data->dev, ret,
> > +				     "Failed to read status register.\n");
> > +
> > +	if (reg & BMP280_REG_STATUS_IM_UPDATE)
> > +		return dev_err_probe(data->dev, ret,
> > +				     "Failed to copy NVM contents.\n");
> 
> ret is 0 at this point.
> Should a -E<something> be used instead?
> 
> CJ
> 

Hi Cristophe,

Yes, actually this could be an I/O error since we were not able to
copy the values back from the NVM device to the sensor.

Cheers,
Vasilis

> > +
> > +	return 0;
> > +}
> > +
> >   static int bmp280_chip_config(struct bmp280_data *data)
> >   {
> >   	u8 osrs = FIELD_PREP(BMP280_OSRS_TEMP_MASK, data->oversampling_temp + 1) |
> > @@ -1082,6 +1106,7 @@ const struct bmp280_chip_info bmp280_chip_info = {
> >   	.read_temp = bmp280_read_temp,
> >   	.read_press = bmp280_read_press,
> >   	.read_calib = bmp280_read_calib,
> > +	.preinit = bmp280_preinit,
> >   	.trigger_handler = bmp280_trigger_handler,
> >   };
> > @@ -1202,6 +1227,7 @@ const struct bmp280_chip_info bme280_chip_info = {
> >   	.read_press = bmp280_read_press,
> >   	.read_humid = bme280_read_humid,
> >   	.read_calib = bme280_read_calib,
> > +	.preinit = bmp280_preinit,
> >   	.trigger_handler = bme280_trigger_handler,
> >   };
> > diff --git a/drivers/iio/pressure/bmp280.h b/drivers/iio/pressure/bmp280.h
> > index 4e675401d61b..73516878d020 100644
> > --- a/drivers/iio/pressure/bmp280.h
> > +++ b/drivers/iio/pressure/bmp280.h
> > @@ -205,6 +205,9 @@
> >   #define BMP280_REG_CONFIG		0xF5
> >   #define BMP280_REG_CTRL_MEAS		0xF4
> >   #define BMP280_REG_STATUS		0xF3
> > +#define BMP280_REG_STATUS_IM_UPDATE	BIT(0)
> > +#define BMP280_REG_RESET		0xE0
> > +#define BMP280_RST_SOFT_CMD		0xB6
> >   #define BMP280_REG_COMP_TEMP_START	0x88
> >   #define BMP280_COMP_TEMP_REG_COUNT	6
>