backlight: backlight: Add backlight_is_blank()

Browse source

The backlight support has three properties that express the state:
 - power
 - state
 - fb_blank

It is un-documented and easy to get wrong.
Add backlight_is_blank() helper to make it simpler
for drivers to get the check of the state correct.

A lot of drivers also includes checks for fb_blank.
This check is redundant when the state is checked
and thus not needed in this helper function.
But added anyway to avoid introducing subtle bugs
due to the creative use of fb_blank in some drivers.
Introducing this helper will for some drivers results in
added support for fb_blank. This will be a change in
functionality, which will improve the backlight driver.

Rolling out this helper to all relevant backlight drivers
will eliminate almost all accesses to fb_blank.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

...

This commit is contained in:

Sam Ravnborg 2020-07-19 10:07:26 +02:00 • committed by Lee Jones

parent 4edfe2248d

commit 1c91b46555

1 changed files with 19 additions and 0 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

19

include/linux/backlight.h

View file