“Outdated/bizarre laptops” sought to assist check Linux kernel backlight drivers

Enlarge / Should you’ve bought a laptop computer that is the right age, like this…

“Outdated/bizarre laptops” sought to assist check Linux kernel backlight drivers
“Outdated/bizarre laptops” sought to assist check Linux kernel backlight drivers
Enlarge / Should you’ve bought a laptop computer that is the right age, like this 2014 pile-up at a recycling program, or a bit “bizarre,” you possibly can assist check it towards proposed modifications to the Linux kernel’s backlight techniques.

Do you may have a laptop computer that is both “fairly previous” or “bizarre in another method”? Did it ship with out Home windows from the manufacturing facility, or did you flash its firmware with coreboot? You possibly can assist the Linux kernel transfer its backlight code ahead with out abandoning quirky gear like yours.

Hans de Goede, a longtime Linux developer and principal engineer at Crimson Hat, writes on his Livejournal about the necessity to check “a particular group of laptops” to stop their backlight controls from disappearing in Linux kernel 6.1.

Outdated laptop computer assessments are wanted as a result of de Goede is initiating some main modifications to user-space backlight controls, one thing he has been engaged on since 2014. As detailed at Linux weblog Phoronix, there are a number of points with how Linux tries to deal with the wide range of backlight schemes in shows, which de Goede laid out on the current Linux Plumbers Convention. There may be a number of backlight units working a single show, leaving high-level controls to “guess which one will work.” Brightness management requires root permissions for the time being. And “0” handed alongside as a backlight worth stays a conundrum, because the engineer identified in 2014: Is that solely off, or as little as the show may be lit?

The modifications that de Goede has proposed for kernel 6.1 would permit for setting most brightness quantities, speaking clearly when brightness controls should not supported, and responding to hotplug occasions, like plugging in a monitor that helps a distinct brightness management scheme.

In case your (previous, bizarre) laptop computer is working Linux already, or you possibly can boot it right into a dwell USB session, you possibly can verify to see in case your laptop computer is likely to be affected by working ls /sys/class/backlight. If there’s just one entry, and it is named intel_backlight, nouveau_bl, amdgpu_bl0, or radeon_bl0, there’s an opportunity your laptop computer may very well be affected by the massive upcoming backlight change. To check additional, comply with the directions in de Goede’s publish.

As seen in a current emergency replace to the Linux kernel, offering the appropriate code to correctly energy a laptop computer show is a difficult affair. There are plenty of laptop computer shows on the market, and the kernel authors and maintainers cannot check all of them. Should you’ve bought an previous one you possibly can boot into Linux, you may be capable to assist.