For some reason the kernel detects an `acpi_video0` in /sys/class/backlight even though it is running in a desktop computer whose monitors don't support editing backlight levels on software.
`/sys/class/backlight/acpi_video0/device` is a symlink to the integrated graphic card, listed on `lspci` as the following:
00:02.0 VGA compatible controller: Intel Corporation Xeon E3-1200 v2/3rd Gen Core processor Graphics Controller (rev 09)
This is causing GNOME to display brightness controls on my computer which does not support them.
please attach the acpidump output.
Created attachment 150421 [details]
I can think of two ways to solve this problem:
1 Add your system into a DMI table to disable the acpi video interface;
2 Disable acpi video interface for all systems that are desktops, which can be queried from the "PM Profile" field of the FADT table.
I think we can try option 2.
Please notice some desktops have brightness interfaces indeed, e.g. HP All in One or iMac computers.
And that acpi_video interface actually works? If that is the case, we can only do quirk then...
For my desktop computer without brightness interface, obviously not. About the all in one computers mentioned above, I don't know.
I faintly recall using once Linux in an iMac, but I don't recall whether brightness controls worked or not.
Anyway, I don't think breaking the brightness interface for such computers is a good idea.
I don't see a way to solve this problem exposed by firmware, I'll close the bug as will_not_fix.