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. > > 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. Thanks. -- Dmitry
