HID: wacom: Initialize brightness of LED trigger

If an LED has a default_trigger set prior to being registered with
the subsystem, that trigger will be executed with a brightness value
defined by `trigger->brightness`. Our driver was not setting this
value, which was causing problems. It would cause the selected LED
to be turned off, as well as corrupt the hlv/llv values assigned to
other LEDs (since calling `wacom_led_brightness_set` will overite
these values).

This patch sets the value of `trigger->brightness` to an appropriate
value. We use `wacom_leds_brightness_get` to transform the llv/hlv
values into a brightness that is understood by the rest of the LED
subsystem.

Fixes: 822c91e72eac ("leds: trigger: Store brightness set by led_trigger_event()")
Cc: [e-mail] # v6.10+
Signed-off-by: Jason Gerecke <[e-mail]>
Signed-off-by: Jiri Kosina <[e-mail]>

drivers/hid/wacom_sys.c

···
 	if (!name)
 		return -ENOMEM;
 
-	if (!read_only) {
-		led->trigger.name = name;
-		error = devm_led_trigger_register(dev, &led->trigger);
-		if (error) {
-			hid_err(wacom->hdev,
-				"failed to register LED trigger %s: %d\n",
-				led->cdev.name, error);
-			return error;
-		}
-	}
-
 	led->group = group;
 	led->id = id;
 	led->wacom = wacom;
···
 		led->cdev.default_trigger = led->cdev.name;
 	} else {
 		led->cdev.brightness_set = wacom_led_readonly_brightness_set;
+	}
+
+	if (!read_only) {
+		led->trigger.name = name;
+		if (id == wacom->led.groups[group].select)
+			led->trigger.brightness = wacom_leds_brightness_get(led);
+		error = devm_led_trigger_register(dev, &led->trigger);
+		if (error) {
+			hid_err(wacom->hdev,
+				"failed to register LED trigger %s: %d\n",
+				led->cdev.name, error);
+			return error;
+		}
 	}
 
 	error = devm_led_classdev_register(dev, &led->cdev);