On Fri, 18 Dec 2020 19:12:30 +0200 Cristian Pop <cristian.pop@xxxxxxxxxx> wrote: > New interface is proposed for dither functionality. This future allows > composing an external signals to the selected output channel. > The dither signal can be turned on/off, scaled, inverted, or it can be > selected from different sources. > > Signed-off-by: Cristian Pop <cristian.pop@xxxxxxxxxx> Coming together nicely though a few more thoughts came to mind when reading this. Only significant one is whether we are better with decimal scaling than percentage scaling for consistency with channel scales etc? Jonathan > --- > Changelog v4: > - Change to "in_voltageY_dither_enable" > - Change scale to numbers + 100% for no scaling > - Possible dither source values: 0 - N0, 1 - N1 > .../ABI/testing/sysfs-bus-iio-dac-ad5766 | 36 +++++++++++++++++++ > 1 file changed, 36 insertions(+) > create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-dac-ad5766 > > diff --git a/Documentation/ABI/testing/sysfs-bus-iio-dac-ad5766 b/Documentation/ABI/testing/sysfs-bus-iio-dac-ad5766 > new file mode 100644 > index 000000000000..72100edb88bb > --- /dev/null > +++ b/Documentation/ABI/testing/sysfs-bus-iio-dac-ad5766 > @@ -0,0 +1,36 @@ > +What: /sys/bus/iio/devices/iio:deviceX/in_voltageY_dither_pwr in_voltageY_dither_en would be more consistent with existing ABI naming. > +KernelVersion: > +Contact: linux-iio@xxxxxxxxxxxxxxx > +Description: > + Dither enable. Write 1 to enable dither or 0 to disable it. > + > +What: /sys/bus/iio/devices/iio:deviceX/in_voltageY_dither_invert > +KernelVersion: > +Contact: linux-iio@xxxxxxxxxxxxxxx > +Description: > + Inverts the dither applied to the selected DAC channel. Dither is not > + inverted by default. Write "1" to invert dither. > + > +What: /sys/bus/iio/devices/iio:deviceX/in_voltageY_dither_scale_available > +KernelVersion: > +Contact: linux-iio@xxxxxxxxxxxxxxx > +Description: > + Returns possible scalings available for the current channel: Given this one is self defining and may well get generalized to other devices I'd got with a description that doesn't provide values. Returns possible scalings as percentages. However, thinking more on this it's a bit inconsistent with other scale values we have which are given in decimal. Would "1 0.75 0.5 0.25" work as well here? > + "100 75 50 25" scaling. > + > +What: /sys/bus/iio/devices/iio:deviceX/in_voltageY_dither_scale > +KernelVersion: > +Contact: linux-iio@xxxxxxxxxxxxxxx > +Description: > + Scales the dither before it is applied to the selected channel: > + 100 - No scaling > + 75 - 75% scaling > + 50 - 50% scaling > + 25 - 25% scaling As above, I'm don't really see an advantage in providing the values. Any userspace ought to cope with any (finding out what is there via _available). "Scales the dither before it is applied to the selected channel. 1 corresponds to no scaling". > + > +What: /sys/bus/iio/devices/iio:deviceX/in_voltageY_dither_source > +KernelVersion: Please fill in the expected kernel version. I'll fix it if this happens to merge near the change over in a cycle, but it's easier to fix something that is there than to add it from scratch :) > +Contact: linux-iio@xxxxxxxxxxxxxxx > +Description: > + Selects dither source applied to the selected channel. Write "0" to > + select N0 source, write "1" to select N1 source.
