On Sun, 2025-05-11 at 00:28 +0800, Larry Wei wrote: > P.S. And I suspect that this change has been affecting all non-Intel and > non-AMD machines for a long time, as there is no "non-free-firmware" > suitable for them.
No, not quite. By default the ACPI video driver relies on the native graphics driver to detect which display(s) have a backlight, and to decide whether they should be controlled via ACPI or via the display controller. According to <https://linux-hardware.org/?probe=58facb533d> there is no native driver loaded on your system for the graphics device. Probably the EFI framebuffer driver is being used instead. This has no knowledge of what kind of display is being used and cannot configure the ACPI video driver properly. So the real fix for this would be for Zhaoxin to get their Linux graphics driver (zx) upstream. The immediate problem I see with that is that it's under GPL v3 which is not compatible with the kernel's GPL v2. But they as copyright holder should be able to relicense it. Ben. -- Ben Hutchings Tomorrow will be cancelled due to lack of interest.
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