Hi Sicelo and David, On Sat, Nov 18, 2023 at 06:09:18PM -0600, David Lechner wrote: > On Fri, Nov 17, 2023 at 12:22 PM Sicelo <absicsz@xxxxxxxxx> wrote: > > > > Hi > > > > Some phones have 1-bit proximity sensors, which simply toggle a GPIO > > line to indicate that an object is near or far. Thresholds are set at > > hardware level. One such sensor is OSRAM SFH 7741 [1], which is used on > > the Nokia N900. > > > > It is currently exported over evdev, emitting the SW_FRONT_PROXIMITY key > > code [2]. > > > > So the question is: should a new, general purpose iio-gpio driver be > > written, that would switch such a proximity sensor to the iio framework? > > Or evdev is really the best place to support it? > > > > There are a couple of people who are willing to write such an iio > > driver, if iio is the way to go. > > > > Regards, > > Sicelo > > > > [1] https://media.digikey.com/pdf/Data%20Sheets/Osram%20PDFs/SFH_7741.pdf > > [2] https://elixir.bootlin.com/linux/v6.6.1/source/arch/arm/boot/dts/ti/omap/omap3-n900.dts#L111 > > > Since this is really a proximity switch (it is either on or off) > rather than measuring a proximity value over a continuous range, it > doesn't seem like a good fit for the iio subsystem. If the sensor is > on a phone, then it is likely to detect human presence so the input > subsystem does seem like the right one for that application. > > More at https://www.kernel.org/doc/html/latest/driver-api/iio/intro.html > I tend to agree; if there are only two discrete states as is the case for a GPIO, then this is technically a switch and not a sensor. Therefore, input seems like a better fit; that is just my $.02. FWIW, a similar discussion came up a few years ago in [1] and again the key differentiator was whether the output is discrete or continuous. Kind regards, Jeff LaBundy [1] https://lore.kernel.org/linux-iio/9f9b0ff6-3bf1-63c4-eb36-901cecd7c4d9@xxxxxxxxxx/
