[PATCH 1/2] video: backlight: make backlight_class constant

Ricardo B. Marliere
2024-03-05T12:21:26Z

Since commit 43a7206b0963 ("driver core: class: make class_register() take
a const *"), the driver core allows for struct class to be in read-only
memory, so move the backlight_class structure to be declared at build time
placing it into read-only memory, instead of having to be dynamically
allocated at boot time.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ricardo B. Marliere <ricardo@marliere.net>
---
drivers/video/backlight/backlight.c | 29 ++++++++++++++++-------------
1 file changed, 16 insertions(+), 13 deletions(-)

diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
index 86e1cdc8e369..d2feaebfd84a 100644
--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -317,8 +317,6 @@ static ssize_t scale_show(struct device *dev,
}
static DEVICE_ATTR_RO(scale);

-static struct class *backlight_class;
-
#ifdef CONFIG_PM_SLEEP
static int backlight_suspend(struct device *dev)
{
@@ -369,6 +367,12 @@ static struct attribute *bl_device_attrs[] = {
};
ATTRIBUTE_GROUPS(bl_device);

+static const struct class backlight_class = {
+ .name = "backlight",
+ .dev_groups = bl_device_groups,
+ .pm = &backlight_class_dev_pm_ops,
+};
+
/**
* backlight_force_update - tell the backlight subsystem that hardware state
* has changed
@@ -418,7 +422,7 @@ struct backlight_device *backlight_device_register(const char *name,
mutex_init(&new_bd->update_lock);
mutex_init(&new_bd->ops_lock);

- new_bd->dev.class = backlight_class;
+ new_bd->dev.class = &backlight_class;
new_bd->dev.parent = parent;
new_bd->dev.release = bl_device_release;
dev_set_name(&new_bd->dev, "%s", name);
@@ -510,7 +514,7 @@ struct backlight_device *backlight_device_get_by_name(const char *name)
{
struct device *dev;

- dev = class_find_device_by_name(backlight_class, name);
+ dev = class_find_device_by_name(&backlight_class, name);

return dev ? to_backlight_device(dev) : NULL;
}
@@ -678,7 +682,7 @@ 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);
+ dev = class_find_device(&backlight_class, NULL, node, of_parent_match);

return dev ? to_backlight_device(dev) : NULL;
}
@@ -746,20 +750,19 @@ EXPORT_SYMBOL(devm_of_find_backlight);

static void __exit backlight_class_exit(void)
{
- class_destroy(backlight_class);
+ class_unregister(&backlight_class);
}

static int __init backlight_class_init(void)
{
- backlight_class = class_create("backlight");
- if (IS_ERR(backlight_class)) {
- pr_warn("Unable to create backlight class; errno = %ld\n",
- PTR_ERR(backlight_class));
- return PTR_ERR(backlight_class);
+ int ret;
+
+ ret = class_register(&backlight_class);
+ if (ret) {
+ pr_warn("Unable to create backlight class; errno = %d\n", ret);
+ return ret;
}

- backlight_class->dev_groups = bl_device_groups;
- backlight_class->pm = &backlight_class_dev_pm_ops;
INIT_LIST_HEAD(&backlight_dev_list);
mutex_init(&backlight_dev_list_mutex);
BLOCKING_INIT_NOTIFIER_HEAD(&backlight_notifier);

--
2.43.0