On Mon, Apr 16, 2018 at 01:07:50PM +0200, Hans de Goede wrote: > On 16-04-18 00:54, James Hogan wrote: > > On Sun, Apr 15, 2018 at 02:04:26PM +0200, Hans de Goede wrote: > > > When you say quirk do you mean you add something to > > > the kernel commandline to work around this? > > > > No, it was automatic, in the source. I don't know this code well enough > > to know how they got it working. > > Weird, if my only_lcd changes impact you then acpi_osi_is_win8() > returns true for you It rings a bell that this laptop claims win8 support. > you should get the intel backlight interface > by default, but maybe the i915 driver somehow detects that that > is not appropriate on your device ... ? > > Before I can start working on a quirk to fix this I've some > questions: > > 1) With recent kernels without the 965736ee654d commit, what is > the output of "ls /sys/class/backlight" ? $ ls -l /sys/class/backlight total 0 lrwxrwxrwx 1 root root 0 Apr 16 13:57 acpi_video0 -> ../../devices/pci0000:00/0000:00:02.0/backlight/acpi_video0 > 2) What is the output of "ls /sys/class/backlight" after > commit 965736ee654d ? no devices show up there. > 3) Can you start a kernel with commit 965736ee654d in there and > "video.only_lcd=0" on the kernel commandline and verify that > this fixes backlight control for you ? Confirmed, acpi_video0 shows up and backlight control works as expected. Cheers James
Attachment:
signature.asc
Description: PGP signature
