On Fri, 9 Nov 2012 15:04:38 +0100
Thierry Reding [off-list ref] wrote:
quoted hunk ↗ jump to hunk
This function finds the struct backlight_device for a given device tree
node. A dummy function is provided so that it safely compiles out if OF
support is disabled.
Signed-off-by: Thierry Reding <redacted>
---
drivers/video/backlight/backlight.c | 17 +++++++++++++++++
include/linux/backlight.h | 10 ++++++++++
2 files changed, 27 insertions(+)
diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
index 297db2f..0d1ed4f 100644
--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -370,6 +370,23 @@ void backlight_device_unregister(struct backlight_device *bd)
}
EXPORT_SYMBOL(backlight_device_unregister);
+#if IS_ENABLED(CONFIG_OF)
Using IS_ENABLED() was odd. We'll never support CONFIG_OF=m, so can't
we use plain old "#ifdef CONFIG_OF" here?
--- a/drivers/video/backlight/backlight.c~backlight-add-of_find_backlight_by_node-function-fix
+++ a/drivers/video/backlight/backlight.c
@@ -370,7 +370,7 @@ void backlight_device_unregister(struct
}
EXPORT_SYMBOL(backlight_device_unregister);
-#if IS_ENABLED(CONFIG_OF)
+#ifdef CONFIG_OF
static int of_parent_match(struct device *dev, void *data)
{
return dev->parent && dev->parent->of_node = data;
--- a/include/linux/backlight.h~backlight-add-of_find_backlight_by_node-function-fix
+++ a/include/linux/backlight.h@@ -134,7 +134,7 @@ struct generic_bl_info {
void (*kick_battery)(void);
};
-#if IS_ENABLED(CONFIG_OF)
+#ifdef CONFIG_OF
struct backlight_device *of_find_backlight_by_node(struct device_node *node);
#else
static inline struct backlight_device *_
quoted hunk ↗ jump to hunk
+static int of_parent_match(struct device *dev, void *data)
+{
+ return dev->parent && dev->parent->of_node = data;
+}
+
+struct backlight_device *of_find_backlight_by_node(struct device_node *node)
+{
+ struct device *dev;
+
+ dev = class_find_device(backlight_class, NULL, node, of_parent_match);
+
+ return dev ? to_backlight_device(dev) : NULL;
+}
+EXPORT_SYMBOL(of_find_backlight_by_node);
It's a global, exported-to-modules function. We should document such
major interfaces. Unless they are dead trivial, but I don't think this
one is that simple. The semantics of the return value could be
explained, and callers should be told that of_find_backlight_by_node()
took a ref on the returned device, and that they need to run
put_device(retval->dev), if retval was not NULL.
And anything else which might be useful.