Hi Jonathan, > From: Jonathan Cameron <jic23@xxxxxxxxxx> > Sent: Sunday, January 16, 2022 12:52 PM > To: Pop, Cristian <Cristian.Pop@xxxxxxxxxx> > Cc: linux-iio@xxxxxxxxxxxxxxx; linux-gpio@xxxxxxxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; > robh+dt@xxxxxxxxxx > Subject: Re: [PATCH v2 2/2] one-bit-adc-dac: Add initial version of one > bit ADC-DAC > > [External] > > On Tue, 11 Jan 2022 13:59:19 +0200 > Cristian Pop <cristian.pop@xxxxxxxxxx> wrote: > > > This allows remote reading and writing of the GPIOs. This is useful in > > application that run on another PC, at system level, where multiple > iio > > devices and GPIO devices are integrated together. > Hi Cristian, > > So I fully understand why this can be useful, but it is a software only > construction so I'm not convinced that it makes sense to necessarily > configure it via device tree. A better fit may well be configfs. > (note I always meant to add configfs controls for iio_hwmon but > haven't > found the time to do it yet...) > > As it currently stands, doing only polled / sysfs reads this driver doesn't > do enough to justify its existence. You could just do all this in > userspace > using the existing gpio interfaces. So to be useful I'd expect it to > at least do triggered buffer capture. > > When we have talked about handling digital signals int he past we > discussed > whether the IIO channel description would also benefit from tighter > packing > than the current minimum of a byte per channel. Perhaps we don't That reminded me about this series [1] Alex tried to upstream. It's slightly related and this was all about supporting buffered channels with less than 8 bits (IIRC). I didn't went through the all thread but I remember you had some "questions" about the whole thing. That series is something that I definitely want to revive at some point (might be that I just need to change things in ADI kernel) to stop having these custom patches in our tree. > technically > 'need' it here but if we do add it in future it will be hard to retrofit into > this driver without big userspace ABI changes (i.e. breaking all existing > users). I think this is the perfect opportunity to add support for it (either with the series I mentioned or something else) if we ever really want to have this in IIO. [1]: https://lore.kernel.org/linux-iio/20200424051818.6408-1-alexandru.ardelean@xxxxxxxxxx/ - Nuno Sá
