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wolf-yuan

Member

Registered: 2025-12-18

Posts: 5

ASUS Zenbook S14 (UX5406SA) ALS IIO device is not detected

Hi,

I recently got my hands on a ASUS Zenbook S14 laptop (model number UX5406SA). Everything been working so far but I cannot get ALS device to be detected.

Following is output of

/sys/bus/iio/devices

/sys/bus/iio/devices
❯ ls iio:device0/
drwxr-xr-x    - root 20 Dec 15:15  buffer
drwxr-xr-x    - root 20 Dec 15:15  buffer0
lrwxrwxrwx    - root 20 Dec 15:15  firmware_node -> ../../../../../../../../LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/device:24/device:25/device:2a
drwxr-xr-x    - root 20 Dec 15:15  physical_location
drwxr-xr-x    - root 20 Dec 15:15  power
drwxr-xr-x    - root 20 Dec 15:15  scan_elements
lrwxrwxrwx    - root 20 Dec 15:15  subsystem -> ../../../../../../../../../bus/iio
drwxr-xr-x    - root 20 Dec 15:15  trigger
.r--r--r-- 4.1k root 20 Dec 15:15 ? dev
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_attention_hysteresis
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_attention_input
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_attention_offset
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_attention_sampling_frequency
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_attention_scale
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_proximity0_hysteresis
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_proximity0_offset
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_proximity0_raw
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_proximity0_sampling_frequency
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_proximity0_scale
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_proximity1_hysteresis
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_proximity1_offset
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_proximity1_raw
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_proximity1_sampling_frequency
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_proximity1_scale
.r--r--r-- 4.1k root 20 Dec 15:15 ? name
.rw-r--r-- 4.1k root 20 Dec 15:15 ? uevent
.r--r--r-- 4.1k root 20 Dec 15:15 ? waiting_for_supplier

/sys/bus/iio/devices
❯ ls iio:device1/
drwxr-xr-x    - root 20 Dec 15:15  buffer
drwxr-xr-x    - root 20 Dec 15:15  buffer0
lrwxrwxrwx    - root 20 Dec 15:15  firmware_node -> ../../../../../../../../LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/device:24/device:25/device:2a
drwxr-xr-x    - root 20 Dec 15:15  physical_location
drwxr-xr-x    - root 20 Dec 15:15  power
drwxr-xr-x    - root 20 Dec 15:15  scan_elements
lrwxrwxrwx    - root 20 Dec 15:15  subsystem -> ../../../../../../../../../bus/iio
drwxr-xr-x    - root 20 Dec 15:15  trigger
.r--r--r-- 4.1k root 20 Dec 15:15 ? dev
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_attention_hysteresis
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_attention_input
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_attention_offset
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_attention_sampling_frequency
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_attention_scale
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_proximity0_hysteresis
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_proximity0_offset
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_proximity0_raw
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_proximity0_sampling_frequency
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_proximity0_scale
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_proximity1_hysteresis
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_proximity1_offset
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_proximity1_raw
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_proximity1_sampling_frequency
.rw-r--r-- 4.1k root 20 Dec 15:15 ? in_proximity1_scale
.r--r--r-- 4.1k root 20 Dec 15:15 ? name
.rw-r--r-- 4.1k root 20 Dec 15:15 ? uevent
.r--r--r-- 4.1k root 20 Dec 15:15 ? waiting_for_supplier

But this device does has ambient light sensor, as per product page & Windows able to use the sensor normally.

Banjo536

Member

Registered: 2025-12-12

Posts: 15

Re: ASUS Zenbook S14 (UX5406SA) ALS IIO device is not detected

Install asus-als-dkms from AUR if available or ensure iio-sensor-proxy is installed.
Enable the sensor in BIOS if an option exists.
Check dmesg | grep iio for errors.
Try kernel 6.2+ or latest LTS, as newer kernels include more laptop sensor drivers.
If still undetected, the sensor may require a vendor-specific ACPI driver not yet upstreamed.

This should make ALS appear under /sys/bus/iio/devices and work with iio-sensor-proxy.

wolf-yuan

Member

Registered: 2025-12-18

Posts: 5

Re: ASUS Zenbook S14 (UX5406SA) ALS IIO device is not detected

Install asus-als-dkms from AUR if available

That package has been removed and the code in it is around 10 years old last time I checked it.

Enable the sensor in BIOS if an option exists.
Check dmesg | grep iio for errors.

There's no such options in BIOS. And there's no error regarding iio in kernel log.

I think it requires vendor ACPI driver that is not currently in the kernel, or there's a specific kernel module I didn't install. I'm currently using latest linux version available.

wolf-yuan

Member

Registered: 2025-12-18

Posts: 5

Re: ASUS Zenbook S14 (UX5406SA) ALS IIO device is not detected

Problem is kinda solved by manually installing additional driver from https://github.com/dantmnf/zenbook-s14-linux/

Install instruction at https://github.com/dantmnf/zenbook-s14-linux/issues/14, proceed with caution because it's not a verified source.

Last edited by wolf-yuan (2025-12-21 16:08:39)

wolf-yuan

Member

Registered: 2025-12-18

Posts: 5

Re: ASUS Zenbook S14 (UX5406SA) ALS IIO device is not detected

Update:

I got additional IIO device but it seems like the driver isn't working well, reading value is 0.

❯ ls /sys/bus/iio/devices/iio:device2/
drwxr-xr-x    - root 22 Dec 00:03  buffer
drwxr-xr-x    - root 22 Dec 00:03  buffer0
drwxr-xr-x    - root 22 Dec 00:03  power
drwxr-xr-x    - root 22 Dec 00:03  scan_elements
lrwxrwxrwx    - root 22 Dec 00:03  subsystem -> ../../../../../../../bus/iio
drwxr-xr-x    - root 22 Dec 00:03  trigger
.rw-r--r-- 4.1k root 22 Dec 00:03 ? current_timestamp_clock
.r--r--r-- 4.1k root 22 Dec 00:03 ? dev
.rw-r--r-- 4.1k root 22 Dec 00:03 ? in_chromaticity_hysteresis
.rw-r--r-- 4.1k root 22 Dec 00:03 ? in_chromaticity_hysteresis_relative
.rw-r--r-- 4.1k root 22 Dec 00:03 ? in_chromaticity_offset
.rw-r--r-- 4.1k root 22 Dec 00:03 ? in_chromaticity_sampling_frequency
.rw-r--r-- 4.1k root 22 Dec 00:03 ? in_chromaticity_scale
.rw-r--r-- 4.1k root 22 Dec 00:03 ? in_chromaticity_x_raw
.rw-r--r-- 4.1k root 22 Dec 00:03 ? in_chromaticity_y_raw
.rw-r--r-- 4.1k root 22 Dec 00:03 ? in_colortemp_hysteresis
.rw-r--r-- 4.1k root 22 Dec 00:03 ? in_colortemp_hysteresis_relative
.rw-r--r-- 4.1k root 22 Dec 00:03 ? in_colortemp_offset
.rw-r--r-- 4.1k root 22 Dec 00:03 ? in_colortemp_raw
.rw-r--r-- 4.1k root 22 Dec 00:03 ? in_colortemp_sampling_frequency
.rw-r--r-- 4.1k root 22 Dec 00:03 ? in_colortemp_scale
.rw-r--r-- 4.1k root 22 Dec 00:03 ? in_illuminance_hysteresis
.rw-r--r-- 4.1k root 22 Dec 00:03 ? in_illuminance_hysteresis_relative
.rw-r--r-- 4.1k root 22 Dec 00:03 ? in_illuminance_offset
.rw-r--r-- 4.1k root 22 Dec 00:03 ? in_illuminance_raw
.rw-r--r-- 4.1k root 22 Dec 00:03 ? in_illuminance_sampling_frequency
.rw-r--r-- 4.1k root 22 Dec 00:03 ? in_illuminance_scale
.rw-r--r-- 4.1k root 22 Dec 00:03 ? in_intensity_both_raw
.rw-r--r-- 4.1k root 22 Dec 00:03 ? in_intensity_hysteresis
.rw-r--r-- 4.1k root 22 Dec 00:03 ? in_intensity_hysteresis_relative
.rw-r--r-- 4.1k root 22 Dec 00:03 ? in_intensity_offset
.rw-r--r-- 4.1k root 22 Dec 00:03 ? in_intensity_sampling_frequency
.rw-r--r-- 4.1k root 22 Dec 00:03 ? in_intensity_scale
.r--r--r-- 4.1k root 22 Dec 00:03 ? name
.rw-r--r-- 4.1k root 22 Dec 00:03 ? uevent

wolf-yuan

Member

Registered: 2025-12-18

Posts: 5

Re: ASUS Zenbook S14 (UX5406SA) ALS IIO device is not detected

Confirmed the ALS is broken on my laptop. On Linux it's both hardware and software issue, the missing driver makes IIO device not recognized and sensor itself is also broken.