On Sun, 1 Oct 2017 21:48:16 +0200 Stefan Brüns <[email protected]> wrote:
> Lower bits of the INA219/220 bus voltage register are conversion > status flags, properly mask the value. > > Signed-off-by: Stefan Brüns <[email protected]> Hi, good to find this issue, but the 'right' fix is perhaps a little more complex than present here. Jonathan > --- > > drivers/iio/adc/ina2xx-adc.c | 14 +++++++++++++- > 1 file changed, 13 insertions(+), 1 deletion(-) > > diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c > index f387b972e4f4..361fb4e459d5 100644 > --- a/drivers/iio/adc/ina2xx-adc.c > +++ b/drivers/iio/adc/ina2xx-adc.c > @@ -44,7 +44,6 @@ > > #define INA226_MASK_ENABLE 0x06 > #define INA226_CVRF BIT(3) > -#define INA219_CNVR BIT(1) > > #define INA2XX_MAX_REGISTERS 8 > > @@ -79,6 +78,11 @@ > #define INA226_ITS_MASK GENMASK(5, 3) > #define INA226_SHIFT_ITS(val) ((val) << 3) > > +/* INA219 Bus voltage register, low bits are flags */ > +#define INA219_OVF BIT(0) > +#define INA219_CNVR BIT(1) > +#define INA219_BUS_VOLTAGE_MASK GENMASK(16, 3) > + > /* Cosmetic macro giving the sampling period for a full P=UxI cycle */ > #define SAMPLING_PERIOD(c) ((c->int_time_vbus + c->int_time_vshunt) \ > * c->avg) > @@ -170,6 +174,10 @@ static int ina2xx_read_raw(struct iio_dev *indio_dev, > else > *val = regval; > > + if ((chip->config->chip_id == ina219) && > + (chan->address == INA2XX_SHUNT_VOLTAGE)) > + *val &= INA219_BUS_VOLTAGE_MASK; > + This first case is fine - up to the fact that it should really be shifting it appropriately to not give a false impression of precision. Also correctly unwinding the case below may require some changes here as well as the scale will change. > return IIO_VAL_INT; > > case IIO_CHAN_INFO_OVERSAMPLING_RATIO: > @@ -639,6 +647,10 @@ static int ina2xx_work_buffer(struct iio_dev *indio_dev) > if (ret < 0) > return ret; > > + if ((chip->config->chip_id == ina219) && > + (INA2XX_SHUNT_VOLTAGE + bit == INA2XX_BUS_VOLTAGE)) > + val &= INA219_BUS_VOLTAGE_MASK; > + For this I'm not sure this is the correct fix. The driver should not be lying about the available data when describing the channel. Right now the channel description is: #define INA219_CHAN_VOLTAGE(_index, _address) { \ .type = IIO_VOLTAGE, \ .address = (_address), \ .indexed = 1, \ .channel = (_index), \ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \ BIT(IIO_CHAN_INFO_SCALE) | \ BIT(IIO_CHAN_INFO_INT_TIME), \ .info_mask_shared_by_dir = BIT(IIO_CHAN_INFO_SAMP_FREQ), \ .scan_index = (_index), \ .scan_type = { \ .sign = 'u', \ .realbits = 16, \ .storagebits = 16, \ .endianness = IIO_LE, \ } \ } Reading the datasheet this should be .realbits = 13, .shift = 3, I think Userspace is then responsible for masking and shifting the data to not give a false impression of it's precision. Clearly this with probably have some knock on effects that will also need fixing. > data[i++] = val; > > if (INA2XX_SHUNT_VOLTAGE + bit == INA2XX_POWER)
