On Tue, 28 Jun 2022 06:51:19 +0100 Mauro Carvalho Chehab <mchehab@xxxxxxxxxx> wrote: > Em Mon, 27 Jun 2022 15:09:55 +0100 > Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> escreveu: > > > On Sun, 26 Jun 2022 23:37:45 +0100 > > Mauro Carvalho Chehab <mchehab@xxxxxxxxxx> wrote: > > > > > Em Sun, 26 Jun 2022 17:55:10 +0100 > > > Jonathan Cameron <jic23@xxxxxxxxxx> escreveu: > > > > > > > From: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> > > > > > > > > We can't duplicate the description of sampling_frequency. This device > > > > has some unusual requirements which we solved by giving a > > > > sampling_frequency of 0 special meaning. As such add a note > > > > about this unusual usage to the main documentation. > > > > > > > > Whilst I don't particularly like this resolution, it is the best > > > > I could come up with given earlier discussion on this topic. > > > > > > > > Link: https://lore.kernel.org/linux-iio/20210315101217.00002c50@xxxxxxxxxx/ > > > > Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> > > > > Cc: Fabrice Gasnier <fabrice.gasnier@xxxxxxxxxxx> > > > > --- > > > > Documentation/ABI/testing/sysfs-bus-iio | 3 +++ > > > > Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 | 8 -------- > > > > 2 files changed, 3 insertions(+), 8 deletions(-) > > > > > > > > diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio > > > > index 3e00d7f7ee22..e81ba6f5e1c8 100644 > > > > --- a/Documentation/ABI/testing/sysfs-bus-iio > > > > +++ b/Documentation/ABI/testing/sysfs-bus-iio > > > > @@ -107,6 +107,9 @@ Description: > > > > relevant directories. If it affects all of the above > > > > then it is to be found in the base device directory. > > > > > > > > + The stm32-timer-trigger has the additional characteristic that > > > > + a sampling_frequency of 0 is defined to stop sampling. > > > > + > > > > > > I would actually say something like: > > > > > > A ampling_frequency of 0 means to stop sampling, > > > if supported by the driver. > > > > > > > We actively want to stop people doing this without coming > > to the list and explaining exactly why they need to. The discussion > > around that one exception was long and involved. So we want > > them to have to modify this doc to list their part thus raising > > awareness of them doing this. So far it's in one driver our of many > > (and to use this feature it needs custom userspace as it is > > setting up a complex chain of devices, but for other more conventional > > use, not allowing 0 is fine). > > > > The source of this disagreement is the documentation serves two > > purposes - for userspace code authors and for kernel developers. > > Userspace can just not set the value to 0 if it is generic code. > > > > We could add additional ABI element to make userspace aware, but > > so far only this one device which will run with customer userspace > > uses this. Hence we rely on documentation. > > > OK! > > This actually proves the point that duplicated symbols at ABI cause > troubles, as different implementations could end abusing on what > it would be expected, like in this case ;-) > > Anyway, feel free to add my reviewed-by to this patch. Picked up 2 and 3 of this series. 4 was fixed by someone else. Thanks, Jonathan > > Regards, > Mauro > > > > > Jonathan > > > > > Either way: > > > > > > Reviewed-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx> > > > > > > > > > > What: /sys/bus/iio/devices/iio:deviceX/sampling_frequency_available > > > > What: /sys/bus/iio/devices/iio:deviceX/in_intensity_sampling_frequency_available > > > > What: /sys/bus/iio/devices/iio:deviceX/in_proximity_sampling_frequency_available > > > > diff --git a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 > > > > index c4a4497c249a..05074c4a65e2 100644 > > > > --- a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 > > > > +++ b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 > > > > @@ -90,14 +90,6 @@ Description: > > > > Reading returns the current master modes. > > > > Writing set the master mode > > > > > > > > -What: /sys/bus/iio/devices/triggerX/sampling_frequency > > > > -KernelVersion: 4.11 > > > > -Contact: benjamin.gaignard@xxxxxx > > > > -Description: > > > > - Reading returns the current sampling frequency. > > > > - Writing an value different of 0 set and start sampling. > > > > - Writing 0 stop sampling. > > > > - > > > > What: /sys/bus/iio/devices/iio:deviceX/in_count0_preset > > > > KernelVersion: 4.12 > > > > Contact: benjamin.gaignard@xxxxxx > >
