Librem 14: slow brightness control after EC and coreboot update

It seems to me that the latest firmware update made the screen brightness control slower: If I now press Fn+F5 or Fn+F6 multiple times quickly, it will only actually make some of these steps in changing the display brightness, and ignore some of the presses. This makes it a bit annoying to quickly adjust the brightness.

I use KDE and this happens on both Debian 11 and the new Debian 12. It does not affect changing the brightness to a specific level directly instead of steps (i.e. via the slider in the battery widget).

The change happened after I updated from EC 1.12_2023-02-02 and coreboot 4.18-Purism-1 to EC 1.13_2023-03-22 and coreboot 4.19-Purism-1.

Anyone else noticed something like this? Does it also happen in GNOME?

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Hi @m4lvin, thank you for the thorough report, and sorry that this fell through the cracks. I can reproduce this on Debian 12 KDE and I’m looking into it. It’s definitely more responsive if I downgrade to 4.18-Purism-1, I’ll know more when I’ve looked into it deeply.

It does appear to change the brightness more slowly on GNOME too. It’s not as noticeable as KDE because it still accepts more brightness keypresses while that’s happening, and it catches up to the correct setting. KDE seems to wait for a change to complete before it will respond to another key press.


I tracked this down and submitted this fix for review upstream: I’ll cherry-pick it for our next firmware releases too.

Thanks again for the thorough report! As far as I can tell, this applied to all systems configuring display brightness with Intel GMA.


Many thanks! I updated my L14 and the brightness control is again super fast now :slight_smile: