K 10
svn:author
V 8
cperciva
K 8
svn:date
V 27
2020-04-16T21:56:52.250218Z
K 7
svn:log
V 527
Alert devd when acpi_video brightness changes

On my Dell Latitude 7390 laptop, the brightness hotkeys
(Fn+<up/down arrow>) send ACPI notifications which acpi_video
handles by adjusting its brightness setting; but ACPI does not
actually do anything with the backlight.

Announcing brightness changes via devd makes it possible to close
the loop by triggering the intel_backlight utility to perform the
required backlight adjustment.

Reviewed by:	imp
MFC after:	3 days
Differential Revision:	https://reviews.freebsd.org/D24424

END