Regression: keyboard backlight settings not retained anymore across sleep/wake or power cycles after upgrade to 2.4

[UndeadDevel]

Please identify some basic details to help process the report

After upgrading to NK Heads 2.4 from 2.1 the keyboard backlight settings are not retained anymore; the backlight instead is switched off whenever I wake from S3 standby or cold boot the laptop (it used to always be retained, although S3 didn't work on 2.1).

Strangely, this issue describes the same phenomenon, but is marked as fixed in coreboot 1.7.1...

A. Provide Hardware Details

1. What board are you using (see list of boards here)?
Nitropad NV41

2. Does your computer have a dGPU or is it iGPU-only?

• dGPU
• iGPU-only

3. Who installed Heads on this computer?

• Insurgo
• Nitrokey (original 2.1)
• Purism
• Other provider
• Self-installed (2.4 via internal GUI upgrade function)

4. What PGP key is being used?

• Librem Key
• Nitrokey Pro 2
• Nitrokey Storage
• Yubikey
• Other (Nitrokey 3A Mini)

5. Are you using the PGP key to provide HOTP verification?

• Yes
• No
• I don't know

B. Identify how the board was flashed

1. Is this problem related to updating heads or flashing it for the first time?

• First-time flash
• Updating heads
• Neither, separate issue with the new firmware

2. If the problem is related to an update, how did you attempt to apply the update?

• Using the Heads GUI
• Flashrom via the Recovery Shell
• External flashing

3. How was Heads initially flashed

• External flashing (presumably...NitroKey did it)
• Internal-only / 1vyrain
• Don't know

4. Was the board flashed with a maximized or non-maximized/legacy rom?

• Maximized (presumably)
• Non-maximized / legacy
• I don't know

5. If Heads was externally flashed, was IFD unlocked?

• Yes (presumably)
• No
• Don't know

C. Identify the rom related to this bug report

NK Heads 2.4
1. Did you download or build the rom at issue in this bug report?

• I downloaded it
• I built it

2. If you downloaded your rom, where did you get it from?

• Heads CircleCi
• Purism
• Nitrokey (this GitHub repo)
• Somewhere else (please identify)

Please provide the release number or otherwise identify the rom downloaded

3. If you built your rom, which repository:branch did you use?

• Heads:Master
• Other (please identify)

4. What version of coreboot did you use in building?

• 4.8.1 (current default in heads:master)
• 4.13
• 4.14
• 4.15
• Other (please specify)
• I don't know

5. In building the rom where did you get the blobs?

• No blobs required
• Provided by the company that installed Heads on the device
• Extracted from a backup rom taken from this device
• Extracted from another backup rom taken from another device (please identify the board model)
• Extracted from the online bios using the automated tools provided in Heads
• I don't know

Please describe the problem

Describe the bug
Under 2.1 with QubesOS 4.2 keyboard backlight settings were always retained; on 2.4 this is not the case anymore.

To Reproduce
Steps to reproduce the behavior:

1. Upgrade NV41 to NK Heads 2.4 and turn on keyboard backlight (lowest setting)
2. Observe that keyboard backlight is switched off completely after waking from S3 or poweroff/poweron cycle

Expected behavior
Keyboard backlight settings retained across standby/wake cycles and boot cycles.

[daringer]

reproducing... no idea towards a solution yet

[UndeadDevel]

In case it helps with the diagnosis: when I wake up the system from S3 by opening the lid the keyboard backlight does turn on for a brief moment (less than a second), but then turns off again, so it seems that the setting is retained during sleep but then wiped (or the light turned off) during the waking process.