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alogim
Tux's lil' helper
Joined: 21 Aug 2015
Posts: 131
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 Posted: Fri Oct 05, 2018 7:40 am Post subject: Ambient light sensor to dynamically adjust screen brightness |
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Good morning everyone. I am a (sofar) happy owner of an HP EliteBook 850 G5. Now, this laptop comes with an in-built ambient light sensor on the top of the screen. When I tried the Ubuntu live, it used to work smoothly (whenever the ambient light changed, the screen brightness changed as well).
I would like to be able to get this on Gentoo as well, taking into account the fact that I am currently using Xfce4.
I can see the sensor listed under /sys/bus/iio/devices and under /dev:
| Code: |
➜ / ls /sys/bus/iio/devices
iio:device0 trigger0
➜ / ls /dev | grep iio
iio:device0
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If I enter directory iio:device0, I can see the following: | Code: | ➜ iio:device0 ls
buffer in_illuminance_hysteresis in_illuminance_raw in_illuminance_scale in_intensity_hysteresis in_intensity_sampling_frequency name scan_elements trigger
dev in_illuminance_offset in_illuminance_sampling_frequency in_intensity_both_raw in_intensity_offset in_intensity_scale power subsystem uevent |
Is there a way I can write some kind of utility to manage brightness according to the values available there? Could anyone help me with this?
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Fitzcarraldo
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Joined: 30 Aug 2008
Posts: 2034
Location: United Kingdom
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| Posted: Fri Oct 05, 2018 10:26 am Post subject: |
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There is a kernel module hp-wmi for controlling various things in HP laptops, including the ambient light sensor. If it is not already configured in your kernel, you could configure it (CONFIG_HP_WMI=m) and load the module to see if that works ('modprobe hp-wmi' then 'echo 1 > /sys/devices/platform/hp-wmi/als' to enable the ALS). But, as you say it is working in Ubuntu, before you reconfigure and rebuild your kernel in Gentoo I suggest you boot an Ubuntu LiveCD or LivePendrive to check whether or not the hp-wmi module is loaded in Ubuntu ('lsmod').
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Fitzcarraldo
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Joined: 30 Aug 2008
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Location: United Kingdom
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alogim
Tux's lil' helper
Joined: 21 Aug 2015
Posts: 131
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| Posted: Fri Oct 05, 2018 11:44 am Post subject: |
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| Fitzcarraldo wrote: | | There is a kernel module hp-wmi for controlling various things in HP laptops, including the ambient light sensor. If it is not already configured in your kernel, you could configure it (CONFIG_HP_WMI=m) and load the module to see if that works ('modprobe hp-wmi' then 'echo 1 > /sys/devices/platform/hp-wmi/als' to enable the ALS). But, as you say it is working in Ubuntu, before you reconfigure and rebuild your kernel in Gentoo I suggest you boot an Ubuntu LiveCD or LivePendrive to check whether or not the hp-wmi module is loaded in Ubuntu ('lsmod'). |
I forgot to say that I wrote down all modules used by Ubuntu as well, so I enabled hp_wmi in the kernel right when I installed it. I also had to enable ACPI_ALS and HID_SENSOR_ALS.
If I try to echo 1 on that file (which exists), I get the following error: | Code: | | bash: echo: write error: Invalid argument |
If I try to open the file with nano, I get | Code: | | [ magic_file(als) failed: cannot read `als' (Invalid argument) ] |
_________________
Desktop: Gigabyte X670E Aorus Master - 7950X3D - 2x16 GB - Sapphire RX 7900XTX Vapor-X - 1 TB MP700 - be quiet! 800 FX - Samsung Odyssey Ark 55"
Phone: Samsung Galaxy S22 Ultra - 256 GB - 12 GB |
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