Re: [PATCH v1 0/3] iio: afe: rescale: Add INFO_PROCESSED support
On Tue, 11 Jun 2019 11:02:14 + Peter Rosin wrote: > On 2019-06-11 11:56, Mylène Josserand wrote: > > Hello everyone, > > > > You will find a small series that add the support of processed values > > for iio-rescale driver. > > Thanks to that, it is possible to read processed values in sysfs instead > > of getting only raw and scale values. > > > > Here is an example for a 3v3 voltage reading: > > # cat /sys/bus/iio/devices/iio\:device1/in_voltage0_scale > > 3.791015625 > > # cat /sys/bus/iio/devices/iio\:device1/in_voltage0_raw > > 879 > > # cat /sys/bus/iio/devices/iio\:device1/in_voltage0_input > > 3332 > > > > It is also possible to read directly the processed values using iio-hwmon > > driver (see example in patch03): > > > > # cat /sys/class/hwmon/hwmon0/in1_input > > 3328 > > > > I seperated my series in 3 patches: > >- Patch01: Move the scale conversion into a function to prepare the > >support of IIO_CHAN_INFO_PROCESSED. > >- Patch02: Add the support of IIO_CHAN_INFO_PROCESSED. > >- Patch03: Add an example of the use of hwmon and voltage-divider nodes > >in device-tree. > > > > If you have any feedbacks on it, I will be pleased to read them! > > > The last patch about hwmon has nothing to do with this series, and > should be possible as-is without any code changes. No? AFAICT, > iio_hwmon calls iio_read_channel_processed, which calls > iio_convert_raw_to_processed_unlocked in case IIO_CHAN_INFO_PROCESSES > is not handled by the driver. Is that not working? > > There is also libiio in userspace that provides the scale as a double > and makes the conversion to a processed value trivial, so the series > is really mostly about the convenience of having a human directly > seeing the processed value in sysfs. Right? > > If that is deemed valuable, then I think it should be fixed in a > central location, and not individually for each and every driver. > > Anyway, not my call, just stating my opinion, but those are the > reasons for me not adding a processed channel from the very beginning. I definitely want to fully understand the reasoning behind this proposal. My gut feeling is that it doesn't make sense a sit ends up with two interfaces to the same thing in userspace, which we generally want to avoid. It's really trivial to do the maths in userspace and often doing it in kernel is less accurate, or much more complex. Jonathan > > Cheers, > Peter > > > Best regards, > > Mylène > > > > Mylène Josserand (3): > > iio: afe: rescale: Move scale conversion to new function > > iio: afe: rescale: Add support of CHAN_INFO_PROCESSED > > dt-bindings: iio: afe: Add hwmon example > > > > .../bindings/iio/afe/voltage-divider.txt | 24 ++ > > drivers/iio/afe/iio-rescale.c | 96 > > -- > > 2 files changed, 96 insertions(+), 24 deletions(-) > > >
Re: [PATCH v1 0/3] iio: afe: rescale: Add INFO_PROCESSED support
On 2019-06-11 11:56, Mylène Josserand wrote: > Hello everyone, > > You will find a small series that add the support of processed values > for iio-rescale driver. > Thanks to that, it is possible to read processed values in sysfs instead > of getting only raw and scale values. > > Here is an example for a 3v3 voltage reading: > # cat /sys/bus/iio/devices/iio\:device1/in_voltage0_scale > 3.791015625 > # cat /sys/bus/iio/devices/iio\:device1/in_voltage0_raw > 879 > # cat /sys/bus/iio/devices/iio\:device1/in_voltage0_input > 3332 > > It is also possible to read directly the processed values using iio-hwmon > driver (see example in patch03): > > # cat /sys/class/hwmon/hwmon0/in1_input > 3328 > > I seperated my series in 3 patches: >- Patch01: Move the scale conversion into a function to prepare the >support of IIO_CHAN_INFO_PROCESSED. >- Patch02: Add the support of IIO_CHAN_INFO_PROCESSED. >- Patch03: Add an example of the use of hwmon and voltage-divider nodes >in device-tree. > > If you have any feedbacks on it, I will be pleased to read them! The last patch about hwmon has nothing to do with this series, and should be possible as-is without any code changes. No? AFAICT, iio_hwmon calls iio_read_channel_processed, which calls iio_convert_raw_to_processed_unlocked in case IIO_CHAN_INFO_PROCESSES is not handled by the driver. Is that not working? There is also libiio in userspace that provides the scale as a double and makes the conversion to a processed value trivial, so the series is really mostly about the convenience of having a human directly seeing the processed value in sysfs. Right? If that is deemed valuable, then I think it should be fixed in a central location, and not individually for each and every driver. Anyway, not my call, just stating my opinion, but those are the reasons for me not adding a processed channel from the very beginning. Cheers, Peter > Best regards, > Mylène > > Mylène Josserand (3): > iio: afe: rescale: Move scale conversion to new function > iio: afe: rescale: Add support of CHAN_INFO_PROCESSED > dt-bindings: iio: afe: Add hwmon example > > .../bindings/iio/afe/voltage-divider.txt | 24 ++ > drivers/iio/afe/iio-rescale.c | 96 > -- > 2 files changed, 96 insertions(+), 24 deletions(-) >
[PATCH v1 0/3] iio: afe: rescale: Add INFO_PROCESSED support
Hello everyone, You will find a small series that add the support of processed values for iio-rescale driver. Thanks to that, it is possible to read processed values in sysfs instead of getting only raw and scale values. Here is an example for a 3v3 voltage reading: # cat /sys/bus/iio/devices/iio\:device1/in_voltage0_scale 3.791015625 # cat /sys/bus/iio/devices/iio\:device1/in_voltage0_raw 879 # cat /sys/bus/iio/devices/iio\:device1/in_voltage0_input 3332 It is also possible to read directly the processed values using iio-hwmon driver (see example in patch03): # cat /sys/class/hwmon/hwmon0/in1_input 3328 I seperated my series in 3 patches: - Patch01: Move the scale conversion into a function to prepare the support of IIO_CHAN_INFO_PROCESSED. - Patch02: Add the support of IIO_CHAN_INFO_PROCESSED. - Patch03: Add an example of the use of hwmon and voltage-divider nodes in device-tree. If you have any feedbacks on it, I will be pleased to read them! Best regards, Mylène Mylène Josserand (3): iio: afe: rescale: Move scale conversion to new function iio: afe: rescale: Add support of CHAN_INFO_PROCESSED dt-bindings: iio: afe: Add hwmon example .../bindings/iio/afe/voltage-divider.txt | 24 ++ drivers/iio/afe/iio-rescale.c | 96 -- 2 files changed, 96 insertions(+), 24 deletions(-) -- 2.11.0