Hi, On 11/13/20 7:58 AM, Dmitry Torokhov wrote: > On Thu, Nov 12, 2020 at 10:50:12AM +0100, Hans de Goede wrote: >> 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 ? > > I think it depends on the kernel we use and architecture. On x86 I think > we rely on udev, like this: > > https://chromium.googlesource.com/chromiumos/overlays/board-overlays/+/master/overlay-nocturne/chromeos-base/chromeos-bsp-nocturne/files/udev/99-cros-sx-proximity.rules > > DEVPATH=="*/pci0000:00/0000:00:15.1/*", SYMLINK+="proximity-wifi-right" > DEVPATH=="*/pci0000:00/0000:00:19.1/*", SYMLINK+="proximity-wifi-left" > ATTR{events/in_proximity1_USE_CS1_thresh_either_en}="1" So that results in a symlink under /dev, right ? That seems like it is not really compatible with how most modern userspace discovers hw (through udev). Although I guess code using udev could still lookup the symlink in the udev per device data, this just not feel like a good way forward. > On newer ARM we use "label" attribute in DTS: > > arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi > > ap_sar_sensor: proximity@28 { > compatible = "semtech,sx9310"; > reg = <0x28>; > #io-channel-cells = <1>; > pinctrl-names = "default"; > pinctrl-0 = <&p_sensor_int_l>; > > interrupt-parent = <&tlmm>; > interrupts = <24 IRQ_TYPE_LEVEL_LOW>; > > vdd-supply = <&pp3300_a>; > svdd-supply = <&pp1800_prox>; > > status = "disabled"; > label = "proximity-wifi"; > }; Hmm, interesting. I did not know iio-devices could have a label sysfs attribute (nor that that could be set through device-tree). I was thinking about adding an in_proximity_location sysfs attribute. But using labels (and standardizing a set of label names) will work nicely too. I have no real preference for this either way, so I guess we might as well go with labels to avoid having any unnecessary discrepancies between ChromeOS and whatever we do for the Thinkpad sensors. Is there a know set of labels which ChromeOS is currently using? If we are going to use labels for this it would be good IMHO to define a set of standard labels for this in say Documentation/ABI/testing/sysfs-bus-iio-labels. >> 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). > > One of the sensors we use is sx9310 that I believe can report range, but > I think we configure them to trigger when a threshold is crossed. > > Events are handled by our powerd: > > https://chromium.googlesource.com/chromiumos/platform2/+/master/power_manager/powerd/system/sar_watcher.cc > >> >> Perhaps you can provide an URL to the kernel code implementing these ? > > drivers/iio/proximity/sx9310.c If I'm reading that correctly the it exports a raw "distance" reading and a suggested threshold value for the code interpreting the reading to use. So that would be a bit different then the Thinkpad sensors, but exporting just a 0-1 range for the in_proximity_raw value for the Thinkpad case should not be a problem. Or we could just make it repot 0 and 100 and export a fixed in_proximity_nearlevel of 50, that would make the userspace API more like other proximity sensors. Regards, Hans
