HID: asus: listen to the asus-wmi brightness device instead of creating one

Some ROG laptops expose multiple interfaces for controlling the
keyboard/RGB brightness. This creates a name conflict under
asus::kbd_brightness, where the second device ends up being
named asus::kbd_brightness_1 and they are both broken.

Therefore, register a listener to the asus-wmi brightness device
instead of creating a new one.

Reviewed-by: Luke D. Jones <luke@ljones.dev>
Reviewed-by: Benjamin Tissoires <bentiss@kernel.org>
Reviewed-by: Denis Benato <benato.denis96@gmail.com>
Acked-by: Benjamin Tissoires <bentiss@kernel.org>
Signed-off-by: Antheas Kapenekakis <lkml@antheas.dev>
Link: https://patch.msgid.link/20260122075044.5070-9-lkml@antheas.dev
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

drivers/hid/hid-asus.c

@@ -27,7 +27,6 @@
 #include <linux/hid.h>
 #include <linux/module.h>
 #include <linux/platform_data/x86/asus-wmi.h>
-#include <linux/platform_data/x86/asus-wmi-leds-ids.h>
 #include <linux/input/mt.h>
 #include <linux/usb.h> /* For to_usb_interface for T100 touchpad intf check */
 #include <linux/power_supply.h>
@@ -103,7 +102,7 @@ MODULE_DESCRIPTION("Asus HID Keyboard and TouchPad");
 #define TRKID_SGN       ((TRKID_MAX + 1) >> 1)
 
 struct asus_kbd_leds {
-	struct led_classdev cdev;
+	struct asus_hid_listener listener;
 	struct hid_device *hdev;
 	struct work_struct work;
 	unsigned int brightness;
@@ -495,11 +494,11 @@ static void asus_schedule_work(struct asus_kbd_leds *led)
 	spin_unlock_irqrestore(&led->lock, flags);
 }
 
-static void asus_kbd_backlight_set(struct led_classdev *led_cdev,
+static void asus_kbd_backlight_set(struct asus_hid_listener *listener,
-				   enum led_brightness brightness)
+				   int brightness)
 {
-	struct asus_kbd_leds *led = container_of(led_cdev, struct asus_kbd_leds,
+	struct asus_kbd_leds *led = container_of(listener, struct asus_kbd_leds,
-						 cdev);
+						 listener);
 	unsigned long flags;
 
 	spin_lock_irqsave(&led->lock, flags);
@@ -509,20 +508,6 @@ static void asus_kbd_backlight_set(struct led_classdev *led_cdev,
 	asus_schedule_work(led);
 }
 
-static enum led_brightness asus_kbd_backlight_get(struct led_classdev *led_cdev)
-{
-	struct asus_kbd_leds *led = container_of(led_cdev, struct asus_kbd_leds,
-						 cdev);
-	enum led_brightness brightness;
-	unsigned long flags;
-
-	spin_lock_irqsave(&led->lock, flags);
-	brightness = led->brightness;
-	spin_unlock_irqrestore(&led->lock, flags);
-
-	return brightness;
-}
-
 static void asus_kbd_backlight_work(struct work_struct *work)
 {
 	struct asus_kbd_leds *led = container_of(work, struct asus_kbd_leds, work);
@@ -539,34 +524,6 @@ static void asus_kbd_backlight_work(struct work_struct *work)
 		hid_err(led->hdev, "Asus failed to set keyboard backlight: %d\n", ret);
 }
 
-/* WMI-based keyboard backlight LED control (via asus-wmi driver) takes
- * precedence. We only activate HID-based backlight control when the
- * WMI control is not available.
- */
-static bool asus_kbd_wmi_led_control_present(struct hid_device *hdev)
-{
-	struct asus_drvdata *drvdata = hid_get_drvdata(hdev);
-	u32 value;
-	int ret;
-
-	if (!IS_ENABLED(CONFIG_ASUS_WMI))
-		return false;
-
-	if (drvdata->quirks & QUIRK_ROG_NKEY_KEYBOARD &&
-			dmi_check_system(asus_use_hid_led_dmi_ids)) {
-		hid_info(hdev, "using HID for asus::kbd_backlight\n");
-		return false;
-	}
-
-	ret = asus_wmi_evaluate_method(ASUS_WMI_METHODID_DSTS,
-				       ASUS_WMI_DEVID_KBD_BACKLIGHT, 0, &value);
-	hid_dbg(hdev, "WMI backlight check: rc %d value %x", ret, value);
-	if (ret)
-		return false;
-
-	return !!(value & ASUS_WMI_DSTS_PRESENCE_BIT);
-}
-
 /*
  * We don't care about any other part of the string except the version section.
  * Example strings: FGA80100.RC72LA.312_T01, FGA80100.RC71LS.318_T01
@@ -706,14 +663,11 @@ static int asus_kbd_register_leds(struct hid_device *hdev)
 	drvdata->kbd_backlight->removed = false;
 	drvdata->kbd_backlight->brightness = 0;
 	drvdata->kbd_backlight->hdev = hdev;
-	drvdata->kbd_backlight->cdev.name = "asus::kbd_backlight";
+	drvdata->kbd_backlight->listener.brightness_set = asus_kbd_backlight_set;
-	drvdata->kbd_backlight->cdev.max_brightness = 3;
-	drvdata->kbd_backlight->cdev.brightness_set = asus_kbd_backlight_set;
-	drvdata->kbd_backlight->cdev.brightness_get = asus_kbd_backlight_get;
 	INIT_WORK(&drvdata->kbd_backlight->work, asus_kbd_backlight_work);
 	spin_lock_init(&drvdata->kbd_backlight->lock);
 
-	ret = devm_led_classdev_register(&hdev->dev, &drvdata->kbd_backlight->cdev);
+	ret = asus_hid_register_listener(&drvdata->kbd_backlight->listener);
 	if (ret < 0) {
 		/* No need to have this still around */
 		devm_kfree(&hdev->dev, drvdata->kbd_backlight);
@@ -1102,7 +1056,7 @@ static int __maybe_unused asus_resume(struct hid_device *hdev) {
 
 	if (drvdata->kbd_backlight) {
 		const u8 buf[] = { FEATURE_KBD_REPORT_ID, 0xba, 0xc5, 0xc4,
-				drvdata->kbd_backlight->cdev.brightness };
+				drvdata->kbd_backlight->brightness };
 		ret = asus_kbd_set_report(hdev, buf, sizeof(buf));
 		if (ret < 0) {
 			hid_err(hdev, "Asus failed to set keyboard backlight: %d\n", ret);
@@ -1228,7 +1182,6 @@ static int asus_probe(struct hid_device *hdev, const struct hid_device_id *id)
 	}
 
 	if (is_vendor && (drvdata->quirks & QUIRK_USE_KBD_BACKLIGHT) &&
-	    !asus_kbd_wmi_led_control_present(hdev) &&
 	    asus_kbd_register_leds(hdev))
 		hid_warn(hdev, "Failed to initialize backlight.\n");
 
@@ -1275,6 +1228,8 @@ static void asus_remove(struct hid_device *hdev)
 	unsigned long flags;
 
 	if (drvdata->kbd_backlight) {
+		asus_hid_unregister_listener(&drvdata->kbd_backlight->listener);
+
 		spin_lock_irqsave(&drvdata->kbd_backlight->lock, flags);
 		drvdata->kbd_backlight->removed = true;
 		spin_unlock_irqrestore(&drvdata->kbd_backlight->lock, flags);