From f20b6200aba241ed8f92df4bcb8f6b2b4049f1d7 Mon Sep 17 00:00:00 2001
From: Sam Ravnborg <sam@ravnborg.org>
Date: Sun, 19 Jul 2020 10:07:26 +0200
Subject: backlight: backlight: Add backlight_is_blank()
Git-commit: 1c91b46555aa1dd86331025e62d55d92459e0faf
Patch-mainline: v5.9-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322
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>
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
include/linux/backlight.h | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/include/linux/backlight.h b/include/linux/backlight.h
index 843cb02225da..428c8da5c6f8 100644
--- a/include/linux/backlight.h
+++ b/include/linux/backlight.h
@@ -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);
--
2.29.2