Screen brightness does not revert after opening screen

ill323 · 11-06-2015, 01:02 AM

It's weird.

My laptop is a Thinkpad R500.
I'm attaching it's full dmesg/lspci.

Can you show your dmesg?

eldercitizen · 11-06-2015, 06:44 AM

I'd add "drm.debug=0x7" and check for differences in dmesg, could you post the full dmesgs?

Maybe this patch could help: http://pastebin.com/V4XD6gNJ

(quirk should be mentioned in the dmesg with the kernel parameter above, if not then I probably didn't figure out the pci-ids correctly, please use lspci -vvn)

eldercitizen · 11-06-2015, 07:43 AM

Someone came to the same conclusion: https://bugs.freedesktop.org/show_bug.cgi?id=88325

fiddlesean · 11-06-2015, 07:36 PM

Yes! With your patch on a vanilla 4.1.12 kernel, I get /sys/class/backlight/intel_backlight again, and the backlight works after resume from suspend.

Thanks a bunch, eldercitizen, for all your help!

ill323: It's not weird, it's Apple. They chose to wire the backlight their own way, so it's not a regular i915 backlight. PITA, eh?