Controlling LEDs on ThinkPad T440p

We'll use Linux and ectool and (optionally) pmh7tool from coreboot.

Most of registers documented below should work on other ThinkPads too, but I'm writing and testing this on T440p specifically. And because starting from this generation, ThinkPads lack many LEDs that were present on previous generations (such as Wi-Fi, disk activity, battery state indicator and so on), I don't include them here.


EC LED control register is 0x0c. Bits 0-3 of value is LED number, bits 4-7 is state. Check this out for more info.

Bit mask State
0x80 on
0xc0 blinking rapidly
0xa0 fading in and out
0x00 off

List of LEDs

# Description Supported states
0x0 Power button all
0x6 Fn button on keyboard all except fading
0xa The red dot on the 'i' of the 'ThinkPad' logo on laptop's lid all
0xe Mic mute button on keyboard all except fading

ectool usage example

Suppose you want to make the red dot on the logo to start fading in and out. 0xa0 | 0x0a = 0xaa, so following will do it:

# ectool -w 0x0c -z 0xaa


Some LEDs can be controlled via PMH7, register 0x102.

To clear bit:

# pmh7tool -c 0x102 $bit 

To set bit:

# pmh7tool -s 0x102 $bit
Bit LED description
3 Fn button on keyboard (0=on, 1=off)
4 Audio mute button on keyboard (0=on, 1=off)
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