Hi, On 11/12/20 7:23 AM, Dmitry Torokhov wrote: > On Wed, Oct 07, 2020 at 11:51:05AM +0200, Hans de Goede wrote: >> Hi, >> >> On 10/7/20 10:36 AM, Jonathan Cameron wrote: >>> On Mon, 5 Oct 2020 22:04:27 -0400 >>> Mark Pearson <markpearson@xxxxxxxxxx> wrote: >>> >>>> Adding Nitin, lead for this feature, to the thread >>> >>> +CC linux-input and Dmitry for reasons that will become clear below. >>>> >>>> On 2020-10-03 10:02 a.m., Hans de Goede wrote: >>>>> Hi All, >>>>> >>>>> Modern laptops can have various sensors which are kinda >>>>> like proximity sensors, but not really (they are more >>>>> specific in which part of the laptop the user is >>>>> proximate to). >>>>> >>>>> Specifically modern Thinkpad's have 2 readings which we >>>>> want to export to userspace, and I'm wondering if we >>>>> could use the IIO framework for this since these readings >>>>> are in essence sensor readings: >>>>> >>>>> 1. These laptops have a sensor in the palm-rests to >>>>> check if a user is physically proximate to the device's >>>>> palm-rests. This info will be used by userspace for WWAN >>>>> functionality to control the transmission level safely. >>>>> >>>>> A patch adding a thinkpad_acpi specific sysfs API for this >>>>> is currently pending: >>>>> https://patchwork.kernel.org/patch/11722127/ >>>>> >>>>> But I'm wondering if it would not be better to use >>>>> IIO to export this info. >>> >>> My first thought on this is it sounds more like a key than a sensor >>> (simple proximity sensors fall into this category as well.) > > [ sorry for sitting on this thread for so long ] > > So I think the important question here is if we only ever want yes/no > answer, or if we can consider adjusting behavior of the system based on > the "closeness" of an object to the device, in which case I think IIO is > more flexible. > > FWIW in Chrome OS land we name IIO proximity sensors using a scheme > "proximity-lte", "proximity-wifi", "proximity-wifi-left", > "proximity-wifi-right", etc, and then userspace implements various > policies (SAR, etc) based off it. Interesting, so 2 questions: 1. So your encoding the location in the sensor's parent-device name instead of using a new sysfs attribute for this ? 2. Do these sensors just give a boolean value atm, or do they already report a range ? IIRC one of the objections from the iio folks in the Lenovo case was that booleans are not really a good fit for iio (IIRC they also said we could still use iio for this). Perhaps you can provide an URL to the kernel code implementing these ? >> That is an interesting suggestion. Using the input/evdev API >> would have some advantages such as being able to have a single >> event node for all the proximity switches and then being able >> to pass a fd to that from a privileged process to a non >> privileged one, something which userspace already has >> various infrastructure for. > > I am not sure if multiplexing all proximity switches into one evdev node > is that great option, as I am sure we'll soon have devices with 2x > palmrest switches and being capable finely adjusting transmit power, > etc. Right, so going with iio, together with a naming scheme like used on ChromeOS might indeed be more future proof (and make things easier for running ChromeOS on non ChromeOS hardware and the other way around). Regards, Hans
