Hi, would it make sense to move the HID human presence driver at drivers/iio/light/hid-sensor-prox.c to the input system then? This driver only checks for the "Biometric" (0x2004b0) and "Biometric: Human Presence" (0x2004b1) HID usages. The former has a vendor defined value range, the latter is defined as a boolean switch. See the HID Usage Tables, section 21.1 and 21.6. I take from this discussion that the input subsystem would make more sense for the "Biometric: Human Presence" usage. I just wanted to chime in as there seems to be some older precedent for a binary sensor in the iio subsystem. I tried to get that sensor working for the proximity sensor on my laptop last year. Regards, Philipp Jungkamp On Sat, 2023-11-25 at 22:33 -0600, Jeff LaBundy wrote: > 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/ >
