I have a Dell XPS 13 Laptop (old series) with ArchLinux and Gnome 3.18. I've read in official gnome 3.18 release notes that

If a light sensor is present, GNOME will now automatically adjust the display brightness in order to adjust for the ambient light level.

Can be tested using a ColorHugALS device for those who don't have built in hardware.

Windows 8 compatible hardware is supported.

A switch in the control center's power panel allows automatic display brightness to be turned on/off.

My ambient light sensor is not supported by Linux kernel out of the box, however I have compiled and installed / loaded this module and now my sensor appears as /sys/bus/acpi/devices/ACPI0008:00/. For example I can do

$ cat /sys/bus/acpi/devices/ACPI0008:00/iio\:device0/in_illuminance_raw

and read current raw illuminance.

However this seems not to be detected / supported by gnome as I still don't get a "switch in the control center's power panel" and display brightness is not automatically adjusted.

enter image description here

How can I make it work?

  • @doc_crissti: yes in the mean time I had landed there too... I've installed it from AUR but still no luck. I issued a request here github.com/hadess/iio-sensor-proxy/issues/46 – lviggiani Oct 9 '15 at 12:31
  • Of course I will bit I'm still struggling... – lviggiani Oct 9 '15 at 12:39
  • I'm not allowed to comment and lviggiani's patch answer is correct but the code has changed and this patch is no longer valid for the current git version. A search and replace of in_illuminance_input to in_illuminance_raw in src/drv-iio-poll-light.c will also do the trick. I noticed however that om my Acer S7 the values of _raw are "on the low side" and i suspect that the kernel "corrects" them for known sensors when exposing them in _input. – Milo Feb 21 '16 at 11:58

In the end I managed to get it working thanks to the support of one of the iio-sensor-proxy and kernel developers.

In my case I had to pull iio-sensor-proxy from git and apply this patch:

diff --git a/src/drv-iio-poll-light.c b/src/drv-iio-poll-light.c
index c2c5821..b568e78 100644
--- a/src/drv-iio-poll-light.c
+++ b/src/drv-iio-poll-light.c
@@ -37,7 +37,7 @@ iio_poll_light_discover (GUdevDevice *device)
        return FALSE;

    path = g_build_filename (g_udev_device_get_sysfs_path (device),
-                "in_illuminance_input",
+                "in_illuminance_raw",
    ret = g_file_test (path, G_FILE_TEST_IS_REGULAR);
    g_free (path);
@@ -130,7 +130,7 @@ iio_poll_light_open (GUdevDevice        *device,

    drv_data->interval = get_interval (device);
    drv_data->input_path = g_build_filename (g_udev_device_get_sysfs_path (device),
-                        "in_illuminance_input",
+                        "in_illuminance_raw",

    return TRUE;

Compiled and installed as per README instruction and finally enabled iio-sensor-proxy.service Now I have automatic brightness adjustment working.

Finally, the dev has submitted a patch to linux kernel that in future will enable iio-sensor-proxy working out of the box also on computers having similar ALS without requiring to patch iio-sensor-proxy.

  • 1
    Which version of the Linux kernel will have this update? And without the kernel update, did the software itself have any update to address this? – palswim Jul 15 '17 at 6:39

It worked for me after I installed the "iio-sensor-proxy" package from the aur.

  • On dell xps 13? – lviggiani Oct 13 '15 at 9:26
  • On a Macbook Pro 13 2013 (but this should not matter). Gnome uses iio-sensor-proxy to access the sensors, so it is a requirement If you want to use those. I hope this helped. – Guest Oct 13 '15 at 10:02
  • This package worked on a Lenovo ThinkPad Helix as well to enable dbus events for the ambient light sensor. Thank you! – eduncan911 Jan 31 '16 at 23:06

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