Am 16.10.19 um 05:10 schrieb Rado S: > =- Michael Biebl wrote on Tue 15.Oct'19 at 13:33:15 +0200 -= > >> I can get the current brightness via >>> # cat /sys/class/backlight/intel_backlight/brightness >>> 1500 > > I get 79560. > >> and change it via >>> # echo 2000 > /sys/class/backlight/intel_backlight/brightness > > Setting it via intel to 66666 makes it darker. > >> What's the output you get for your dell_backlight? > >>From dell_backlight I get: > # cat dell_backlight/brightness > 6 > > But when setting it, it says: > > # echo 5 > dell_backlight/brightness > -ksh: echo: write to 1 failed [Input/output error] > > This is what both links look like: > > 0 lrwxrwxrwx 1 root root 0 Oct 16 05:01 dell_backlight -> > ../../devices/platform/dell-laptop/backlight/dell_backlight/ > 0 lrwxrwxrwx 1 root root 0 Oct 16 04:54 intel_backlight -> > ../../devices/pci0000:00/0000:00:02.0/drm/card0/card0-LVDS-1/intel_backlight/ > > dell_backlight/: > total 0 > 0 -r--r--r-- 1 root root 4096 Oct 16 05:03 actual_brightness > 0 -rw-r--r-- 1 root root 4096 Oct 16 05:03 bl_power > 0 -rw-r--r-- 1 root root 4096 Oct 16 05:04 brightness > 0 lrwxrwxrwx 1 root root 0 Oct 16 05:03 device -> ../../../dell-laptop/ > 0 -r--r--r-- 1 root root 4096 Oct 16 05:03 max_brightness > 0 drwxr-xr-x 2 root root 0 Oct 16 05:03 power/ > 0 lrwxrwxrwx 1 root root 0 Oct 16 04:52 subsystem -> > ../../../../../class/backlight/ > 0 -r--r--r-- 1 root root 4096 Oct 16 05:03 type > 0 -rw-r--r-- 1 root root 4096 Oct 16 05:03 uevent > > intel_backlight/: > total 0 > 0 -r--r--r-- 1 root root 4096 Oct 16 04:54 actual_brightness > 0 -rw-r--r-- 1 root root 4096 Oct 16 04:54 bl_power > 0 -rw-r--r-- 1 root root 4096 Oct 16 04:54 brightness > 0 lrwxrwxrwx 1 root root 0 Oct 16 04:54 device -> ../../card0-LVDS-1/ > 0 -r--r--r-- 1 root root 4096 Oct 16 04:54 max_brightness > 0 drwxr-xr-x 2 root root 0 Oct 16 04:54 power/ > 0 lrwxrwxrwx 1 root root 0 Oct 16 04:54 subsystem -> > ../../../../../../../class/backlight/ > 0 -r--r--r-- 1 root root 4096 Oct 16 04:54 type > 0 -rw-r--r-- 1 root root 4096 Oct 16 04:54 uevent > > What next? >
Dunno. You'll probably need to ask someone who is familiar with Dell hardware. I have no idea why these Dell laptops provide a dell_backlight device and what this device supposed to control. Apparently it can't be used to change the brightness despite it exposing the brightness attribute. -- Why is it that all of the instruments seeking intelligent life in the universe are pointed away from Earth?
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