Jonathan Cameron <jic23@xxxxxxxxxx> 於 2022年7月19日 週二 凌晨12:54寫道： > > On Mon, 18 Jul 2022 13:46:03 +0800 > cy_huang <u0084500@xxxxxxxxx> wrote: > > > From: ChiYuan Huang <cy_huang@xxxxxxxxxxx> > > > > Add documentation for the usage of voltage channel integration time. > > > > Signed-off-by: ChiYuan Huang <cy_huang@xxxxxxxxxxx> > > --- > > Documentation/ABI/testing/sysfs-bus-iio | 10 ++++++++++ > > 1 file changed, 10 insertions(+) > > > > diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio > > index d4ccc68..1f7d327 100644 > > --- a/Documentation/ABI/testing/sysfs-bus-iio > > +++ b/Documentation/ABI/testing/sysfs-bus-iio > > @@ -2030,3 +2030,13 @@ Description: > > Available range for the forced calibration value, expressed as: > > > > - a range specified as "[min step max]" > > + > > +What: /sys/bus/iio/devices/iio:deviceX/in_voltageY_integration_time > > +KernelVersion: 5.20 > > +Contact: linux-iio@xxxxxxxxxxxxxxx > > +Description: > > + For voltage sensing hardware, there may be different time between > > + channel conversion and sample update. 'Integration time' is used to > > + specify the channel internal conversion time. And sample update > > + interval is equal to average sample count multiple integration time. > > + Unit as microsecond. > > Whilst I did suggest moving this to this file, I also suggested that it was the > wrong interface to use. For similar cases we've used in_voltageY_sampling_frequency > in the past because this isn't really an integration time, but rather a reflection of > a bunch of other stuff that makes up the conversion time. In IIO we chose a long > time ago to use 1/conversion_time as the exposed interface == sampling_frequency > > So, unless there is a strong reason to do otherwise, drop the overall sampling_frequency > attribute and use per channel ones instead. Then update the main documentation > to make this usecase clear. Something in the block > https://elixir.bootlin.com/linux/latest/source/Documentation/ABI/testing/sysfs-bus-iio#L89 > like adding the in_voltageY_sampling_frequency entry to the What: list and a > sentence at the end that says something like: > > "Some devices have separate controls of sampling frequency for individual channels. > If multiple channels are enabled in a scan, then the sampling_frequency of the the > scan may be computed from the per channel sampling_frequencies." > >From my case, I need to specify in_voltageX_sampling_frequency/in_powerY_sampling_frequency/ in_currentZ_sampling_frequency. And describe all in the same sentence. Can I directly copy the sentence that you described above? I read the comment. The sentence that you wrote seems more generic. If any misunderstanding, please correct me. > Not something to put in the documentation, but for devices which do simultaneous sampling > it is very unlikely we'll have per channel sampling frequencies so there isn't an > ambiguity. The alternative we 'could' consider is to allow both overall sampling_frequency > and per channel in_voltageY_sampling_frequency but that is a bad idea because the > ABI (and most userspace software) assumes that more specific attributes override the > values of more generic ones (rather than them having different meanings as would be > the case here). > > Jonathan
