[PATCH] platform/x86: dell-laptop: don't register platform::micmute if the related tokens don't exist.

[koba.ko@canonical.com]

From: Koba Ko <koba.ko@canonical.com>

On dell G3-3590, error message is issued during boot up,
"platform::micmute: Setting an LED's brightness failed (-19)",
but there's no micmute led on the machine.

Get the related tokens of SMBIOS, GLOBAL_MIC_MUTE_DISABLE/ENABLE.
If one of two tokens doesn't exist,
don't call led_classdev_register() for platform::micmute.
After that, you wouldn't see the platform::micmute in /sys/class/leds/,
and the error message wouldn't see in dmesg.

Signed-off-by: Koba Ko <koba.ko@canonical.com>
---
 drivers/platform/x86/dell-laptop.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/platform/x86/dell-laptop.c b/drivers/platform/x86/dell-laptop.c
index 1e46022fb2c5..afc1ded83e56 100644
--- a/drivers/platform/x86/dell-laptop.c
+++ b/drivers/platform/x86/dell-laptop.c
@@ -2208,10 +2208,13 @@ static int __init dell_init(void)
 
 	dell_laptop_register_notifier(&dell_laptop_notifier);
 
-	micmute_led_cdev.brightness = ledtrig_audio_get(LED_AUDIO_MICMUTE);
-	ret = led_classdev_register(&platform_device->dev, &micmute_led_cdev);
-	if (ret < 0)
-		goto fail_led;
+	if (dell_smbios_find_token(GLOBAL_MIC_MUTE_DISABLE) &&
+	    dell_smbios_find_token(GLOBAL_MIC_MUTE_ENABLE)) {
+		micmute_led_cdev.brightness = ledtrig_audio_get(LED_AUDIO_MICMUTE);
+		ret = led_classdev_register(&platform_device->dev, &micmute_led_cdev);
+		if (ret < 0)
+			goto fail_led;
+	}
 
 	if (acpi_video_get_backlight_type() != acpi_backlight_vendor)
 		return 0;
-- 
2.17.1