I am running a Thinkpad T480 with Ubuntu 16.04 and i want to disable the audio mute led. (This led is on when the sound is muted, which is pretty much all the time).
So far i have followed instruction c-2 of the first answer of the following question: Enabling Mic Mute button and light on Lenovo Thinkpads This allowed me to disable the mic mute light. However it does not allow me to disable the audio mute led.
I have also patched thinkpad_acpi to allow all leds to be changed and added a soundmute value to the tpacpi_led_names. This adds a directory in /sys/clas/leds but setting 0 in the brightness file does not turn off the led.
I used this thinkpad_acpi version for ubuntu-bionic (16.04): https://kernel.ubuntu.com/git/gavinguo/ubuntu-bionic.git/tree/drivers/platform/x86/thinkpad_acpi.c?h=hf203191v20181105b1habae6bf60e7c