On Montag, 17. Juli 2017 22:53:57 CEST Jonathan Cameron wrote: > On Mon, 17 Jul 2017 01:34:10 +0200 > > Stefan Brüns <stefan.bruens@xxxxxxxxxxxxxx> wrote: > > The ina2xx driver appeared in the Linux kernel version 4.5, but provided > > no documentation. Contrary to other uses of resistance in IIO, ina2xx uses > > microohms instead of ohms in the sysfs attribute. > > > > Signed-off-by: Stefan Brüns <stefan.bruens@xxxxxxxxxxxxxx> > > This has me confused. The documentation is already > there and lists it as being in ohms. Which obviously, from reading the source code, is wrong - it uses microohms. Also, the current Description contains IMHO irrelevant stuff: "The value of the shunt resistor may be known only at runtime fom an eeprom content read by a client application." > Ah, subtle filename difference. Docs in are > Documentation/ABI/testing/sysfs-bus-iio-ina2xx-adc Well spotted ... > This attribute effectively exists for other parts > as well now. My grep foo failed me here, the only parts I could find are the MAX9611 (which specifies and uses ohms) and the INA2xx. adc/qcom-spmi-iadc.c allows to read the RSENSE value from device tree (specified in microohms), but does not expose it via sysfs. Can you point me to other devices? Slightly off-topic: Some attributes in iio are read from device-tree (e.g. shunt resistor values), should the iio documentation point to the dt bindings? Currently, only mount_matrix in sysfs-bus-iio vaguely mentions device-tree. Kind regards, Stefan > > --- > > > > Documentation/ABI/testing/sysfs-bus-iio-adc-ina2xx-adc | 7 +++++++ > > 1 file changed, 7 insertions(+) > > create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-adc-ina2xx-adc > > > > diff --git a/Documentation/ABI/testing/sysfs-bus-iio-adc-ina2xx-adc > > b/Documentation/ABI/testing/sysfs-bus-iio-adc-ina2xx-adc new file mode > > 100644 > > index 000000000000..9525098f6822 > > --- /dev/null > > +++ b/Documentation/ABI/testing/sysfs-bus-iio-adc-ina2xx-adc > > @@ -0,0 +1,7 @@ > > +What: /sys/bus/iio/devices/iio:deviceX/in_shunt_resistor > > +Date: December 2015 > > +KernelVersion: 4.5 > > +Contact: linux-iio@xxxxxxxxxxxxxxx > > +Description: The value of the shunt resistor connected to the V_IN+ and > > V_IN- + inputs, used to compute the current flowing through the shunt > > and + the corresponding power. In microohms. -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
