On my Dell XPS 9570 Powerdevil is unable to adjust screen brightness. This is because the laptop has two sysfs entries: $ grep -s . /sys/class/backlight/*/* /sys/class/backlight/acpi_video0/actual_brightness:2 /sys/class/backlight/acpi_video0/bl_power:0 /sys/class/backlight/acpi_video0/brightness:2 /sys/class/backlight/acpi_video0/max_brightness:10 /sys/class/backlight/acpi_video0/scale:unknown /sys/class/backlight/acpi_video0/type:firmware /sys/class/backlight/intel_backlight/actual_brightness:12000 /sys/class/backlight/intel_backlight/bl_power:0 /sys/class/backlight/intel_backlight/brightness:12000 /sys/class/backlight/intel_backlight/max_brightness:120000 /sys/class/backlight/intel_backlight/scale:unknown /sys/class/backlight/intel_backlight/type:raw Writing to acpi_video0/brightness does nothing. Writing to intel_backlight/brightness works. However, the code in daemon/backends/upower/backlighthelper.cpp looks at the “type” parameter and prefers “firmware” to “platform” to “raw”, which, in this case, chooses the wrong device. The error is fixed, at least on my laptop, if I edit the code to make “raw” entries the top preference. Please add more logic to choose the correct sysfs entry or make it user configurable.
Created attachment 143693 [details] please check error attached in image failed to start load/save screen backlight brightness of backlight:acpi_video0. failed to start pkgfile database update.
(In reply to Devaraj Singh from comment #1) > failed to start load/save screen backlight brightness of > backlight:acpi_video0. > failed to start pkgfile database update. That looks entirely unrelated. Please report a new bug instead.
There have been a lot of improvements and bug fixes to brightness control since this report was opened. If you still are experiencing a bug, please open a new report. Thanks.