UbiquitousOS
/
OpenCloudOS-Kernel
mirror of https://gitee.com/OpenCloudOS/OpenCloudOS-Kernel.git
11
0
Fork 0
Code Issues Projects Releases Wiki Activity

backlight: backlight: Add backlight_is_blank() 

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 Stats Download Patch File Download Diff File Expand all files Collapse all files

19
include/linux/backlight.h
View File

@ -175,6 +175,25 @@ static inline void backlight_put(struct backlight_device *bd)
put_device(&bd->dev);
}
/**
* backlight_is_blank - Return true if display is expected to be blank
* @bd: the backlight device
*
* Display is expected to be blank if any of these is true::
*
* 1) if power in not UNBLANK
* 2) if fb_blank is not UNBLANK
* 3) if state indicate BLANK or SUSPENDED
*
* Returns true if display is expected to be blank, false otherwise.
*/
static inline bool backlight_is_blank(const struct backlight_device *bd)
{
return bd->props.power != FB_BLANK_UNBLANK ||
bd->props.fb_blank != FB_BLANK_UNBLANK ||
bd->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK);
}
extern struct backlight_device *backlight_device_register(const char *name,
struct device *dev, void *devdata, const struct backlight_ops *ops,
const struct backlight_properties *props);