@@ -388,7 +388,6 @@ struct backlight_device *backlight_device_register(const char *name,
new_name = kasprintf(GFP_KERNEL, "%s-secondary", name);
if (!new_name)
return ERR_PTR(-ENOMEM);
- put_device(&prev_bd->dev);
}
new_bd->dev.class = &backlight_class;
@@ -428,6 +427,14 @@ struct backlight_device *backlight_device_register(const char *name,
list_add(&new_bd->entry, &backlight_dev_list);
mutex_unlock(&backlight_dev_list_mutex);
+ /* set them until the secondary device is available */
+ if (prev_bd) {
+ prev_bd->secondary = new_bd;
+ new_bd->primary = prev_bd;
+ new_bd->is_secondary = true;
+ put_device(&prev_bd->dev);
+ }
+
kfree(new_name);
return new_bd;
@@ -291,13 +291,42 @@ struct backlight_device {
* @use_count: The number of unblanked displays.
*/
int use_count;
+
+ /**
+ * @is_secondary: Indicates whether this backlight device is secondary.
+ */
+ bool is_secondary;
+
+ /**
+ * @secondary: Pointer to the secondary backlight device.
+ */
+ struct backlight_device *secondary;
+
+ /**
+ * @primary: Pointer to the primary backlight device.
+ *
+ * Non-NULL only for secondary devices.
+ */
+ struct backlight_device *primary;
};
+static inline struct backlight_device *
+to_primary_backlight_device(struct backlight_device *bd)
+{
+ return bd->is_secondary ? bd->primary : bd;
+}
+
+static inline struct backlight_device *
+to_secondary_backlight_device(struct backlight_device *bd)
+{
+ return bd->is_secondary ? bd : bd->secondary;
+}
+
/**
- * backlight_update_status - force an update of the backlight device status
+ * backlight_update_status_single - force an update of the backlight device status
* @bd: the backlight device
*/
-static inline int backlight_update_status(struct backlight_device *bd)
+static inline int backlight_update_status_single(struct backlight_device *bd)
{
int ret = -ENOENT;
@@ -309,6 +338,23 @@ static inline int backlight_update_status(struct backlight_device *bd)
return ret;
}
+/**
+ * backlight_update_status - update primary and secondary backlight devices
+ * @bd: the backlight device
+ */
+static inline int backlight_update_status(struct backlight_device *bd)
+{
+ struct backlight_device *primary = to_primary_backlight_device(bd);
+ struct backlight_device *secondary = to_secondary_backlight_device(bd);
+ int ret;
+
+ ret = backlight_update_status_single(primary);
+ if (!secondary || ret)
+ return ret;
+
+ return backlight_update_status_single(secondary);
+}
+
/**
* backlight_enable - Enable backlight
* @bd: the backlight device to enable
This patch enhances dual-backlight handling by explicitly linking primary and secondary backlight devices using new fields: - `is_secondary`: Marks if a device is secondary in a pair - `secondary`: Points to the associated secondary device (if any) - `primary`: Points to the primary device (for secondary devices) It also update `backlight_update_status()` to ensure that both primary and secondary devices are updated together during brightness changes. This provides a consistent update mechanism in dual-backlight case. Suggested-by: Daniel Thompson <danielt@kernel.org> Signed-off-by: Pengyu Luo <mitltlatltl@gmail.com> --- drivers/video/backlight/backlight.c | 9 +++++- include/linux/backlight.h | 50 +++++++++++++++++++++++++++-- 2 files changed, 56 insertions(+), 3 deletions(-)