[PATCH 2/2] video: backlight: lcd: make lcd_class constant

Ricardo B. Marliere
2024-03-05T12:21:29Z

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 lcd_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/lcd.c | 23 +++++++++++++----------
1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/drivers/video/backlight/lcd.c b/drivers/video/backlight/lcd.c
index 77c5cb2a44e2..ba4771cbd781 100644
--- a/drivers/video/backlight/lcd.c
+++ b/drivers/video/backlight/lcd.c
@@ -159,8 +159,6 @@ static ssize_t max_contrast_show(struct device *dev,
}
static DEVICE_ATTR_RO(max_contrast);

-static struct class *lcd_class;
-
static void lcd_device_release(struct device *dev)
{
struct lcd_device *ld = to_lcd_device(dev);
@@ -175,6 +173,11 @@ static struct attribute *lcd_device_attrs[] = {
};
ATTRIBUTE_GROUPS(lcd_device);

+static const struct class lcd_class = {
+ .name = "lcd",
+ .dev_groups = lcd_device_groups,
+};
+
/**
* lcd_device_register - register a new object of lcd_device class.
* @name: the name of the new object(must be the same as the name of the
@@ -202,7 +205,7 @@ struct lcd_device *lcd_device_register(const char *name, struct device *parent,
mutex_init(&new_ld->ops_lock);
mutex_init(&new_ld->update_lock);

- new_ld->dev.class = lcd_class;
+ new_ld->dev.class = &lcd_class;
new_ld->dev.parent = parent;
new_ld->dev.release = lcd_device_release;
dev_set_name(&new_ld->dev, "%s", name);
@@ -318,19 +321,19 @@ EXPORT_SYMBOL(devm_lcd_device_unregister);

static void __exit lcd_class_exit(void)
{
- class_destroy(lcd_class);
+ class_unregister(&lcd_class);
}

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

- lcd_class->dev_groups = lcd_device_groups;
return 0;
}

--
2.43.0