[PATCH v2 1/5] platform/x86: lg-laptop: Fix LED resource handling

[Armin Wolf <W_Armin@gmx.de>]

The event notification callback might access kbd_backlight even
when it was not successfully registered with the LED subsystem.
The same happens inside acpi_remove(), where the LED devices are
unregistered unconditionally.

Fix this by tracking the availability of the kbd_backlight LED
device and use devm_led_classdev_register() to let devres take
care of unregistering the LED devices during removal. For this
the parent device of the LED devices is changed to the native
platform device.

Fixes: ae26278829a8 ("platform/x86: lg-laptop: Use correct event for keyboard backlight FN-key")
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
---
 drivers/platform/x86/lg-laptop.c | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/drivers/platform/x86/lg-laptop.c b/drivers/platform/x86/lg-laptop.c
index a8f2f465ef3f..a2db9657027e 100644
--- a/drivers/platform/x86/lg-laptop.c
+++ b/drivers/platform/x86/lg-laptop.c
@@ -100,6 +100,7 @@ static u32 inited;
 #define INIT_SPARSE_KEYMAP      0x80
 
 static int battery_limit_use_wmbb;
+static bool kbd_backlight_available;
 static struct led_classdev kbd_backlight;
 static enum led_brightness get_kbd_backlight_level(struct device *dev);
 
@@ -214,6 +215,7 @@ static union acpi_object *lg_wmbb(struct device *dev, u32 method_id, u32 arg1, u
 static void wmi_notify(union acpi_object *obj, void *context)
 {
 	long data = (long)context;
+	unsigned int brightness;
 
 	pr_debug("event guid %li\n", data);
 	if (!obj)
@@ -224,8 +226,11 @@ static void wmi_notify(union acpi_object *obj, void *context)
 		struct key_entry *key;
 
 		if (eventcode == 0x10000000) {
-			led_classdev_notify_brightness_hw_changed(
-				&kbd_backlight, get_kbd_backlight_level(kbd_backlight.dev->parent));
+			if (kbd_backlight_available) {
+				brightness = get_kbd_backlight_level(kbd_backlight.dev->parent);
+				led_classdev_notify_brightness_hw_changed(&kbd_backlight,
+									  brightness);
+			}
 		} else {
 			key = sparse_keymap_entry_from_scancode(
 				wmi_input_dev, eventcode);
@@ -865,8 +870,13 @@ static int acpi_probe(struct platform_device *pdev)
 		goto out_platform_device;
 
 	/* LEDs are optional */
-	led_classdev_register(&pf_device->dev, &kbd_backlight);
-	led_classdev_register(&pf_device->dev, &tpad_led);
+	ret = devm_led_classdev_register(&pdev->dev, &kbd_backlight);
+	if (ret < 0)
+		kbd_backlight_available = false;
+	else
+		kbd_backlight_available = true;
+
+	devm_led_classdev_register(&pdev->dev, &tpad_led);
 
 	wmi_input_setup();
 	battery_hook_register(&battery_hook);
@@ -884,9 +894,6 @@ static void acpi_remove(struct platform_device *pdev)
 {
 	sysfs_remove_group(&pf_device->dev.kobj, &dev_attribute_group);
 
-	led_classdev_unregister(&tpad_led);
-	led_classdev_unregister(&kbd_backlight);
-
 	battery_hook_unregister(&battery_hook);
 	wmi_input_destroy();
 	platform_device_unregister(pf_device);
-- 
2.39.5