Hi Tim,
On 11/1/22 19:30, Tim Crawford via coreboot wrote:
I have tested backlight controls on Pop!_OS 22.04 with Ubuntu mainline kernel 6.1-rc3 (as well as Windows 10) on the following:
- system76/oryp6 (CML-H)
- system76/lemp10 (TGL-U)
- system76/lemp11 (ADL-U)
- system76/oryp9 (ADL-P)
ADL requires hooking up the GMA controls [1], and the mainboards need to specify the gfx in devicetree. With these changes, `acpi_video0` is present and backlight controls work.
Everything else is working as expected. I don't have anything older than CML-H anymore to test on.
Great, thank you for testing!
About the change on the ADL system, I guess that it did work with 6.0 and older Linux kernels, with a /sys/class/backlight/intel_backlight being present then ?
Just wondering. I'm happy to see coreboot adjusted to make the kernels heuristics work. OTOH though coreboot BIOS users really should not need to upgrade their BIOS to stop things breaking with a new kernel.
I'm not entirely sure what the right balance is.
Note that I plan to submit a revert for the patch which hides: /sys/class/backlight/intel_backlight when the acpi_video_get_backlight_type() heuristics say that another backlight interface should be used, since it seems that this will break quite a few (mostly older, beginning of Intel x86_64 era) laptops.
So with the final 6.1 /sys/class/backlight/intel_backlight should stay around, but I do want to try again later since I really want to get rid of the having multiple /sys/class/backlight/ entries for a single panel and then let userspace choose shenanigans.
I've some ideas on how to change the heuristics which will hopefully fix the beginning of Intel x86_64 era laptops, but I don't think those will help on the coreboot using System76 laptops case...
Regards,
Hans