linux-kernel - ThinkPad T480s & LED_MUTE, LED

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Date:   Fri, 8 Jun 2018 13:10:57 +0200
From:   Pali Rohár <pali.rohar@...il.com>
To:     Henrique de Moraes Holschuh <ibm-acpi@....eng.br>,
        ibm-acpi-devel@...ts.sourceforge.net,
        platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: ThinkPad T480s & LED_MUTE, LED_MICMUTE

Hi! With up-to-date thinkpad_acpi.ko driver on ThinkPad T480s I'm seeing
a strange behavior of LEDs which are integrated into mic mute (Fn+F4)
and mute (Fn+F1) keys.

When thinkpad_acpi.ko is not loaded, then mute key is working fine. When
pressed, it correctly generates KEY_MUTE on AT Translated Set 2 keyboard
input device and also turn on/of mute led. But when micmute key is
pressed then, nothing happen. No key event is reported and also led is
not turned on/off.

On the other hand, when thinkpad_acpi.ko is loaded, then both buttons
mute and micmute correctly generates input events; mute via AT keyboard
and micmute via ThinkPad Extra Buttons. But led is not changed. When
thinkpad_acpi.ko is loaded it turn off both leds (mute and micmute) and
leds after pressing any of those buttons, leds are not turned on again.

When thinkpad_acpi.ko is unloaded, then pressing mute button again start
switching led on/off.

So it seems that some init sequence of thinkpad_acpi.ko breaks mute led.
And fini sequence of thinkpad_acpi.ko makes mute led working again.

-- 
Pali Rohár
pali.rohar@...il.com