Backlight buttons not working out of the box on Thinkpad T430 with switchable graphics
Submitted by Erico Nunes
Link to original bug (#773913)
Description
During the "Better Switchable Graphics Support" Fedora test day, while executing the Suspend test (http://fedoraproject.org/wiki/QA:Testcase_intelvideo_suspend) on my Thinkpad T430, the test failed due to display backlight buttons not working out of the box. The Fedora image used is the Test Day live image from https://fedoraproject.org/wiki/Test_Day:2016-11-03_BetterSwitchableGraphicsSupport .
The backlight "window" from gnome shows up and the bar increases/decreases when I press the backlight buttons, however it does not actually change the display backlight. I noticed that when I use the backlight keys, /sys/class/backlight/nv_backlight gets increased/decreased instead of /sys/class/backlight/intel_backlight . Suspend works fine.
halfline helped me to debug this on #fedora-test-day on IRC, below are the chat logs along with output of commands that were requested.
enunes >> hello, I just posted results, backlight buttons don't work out of the box, I noticed that /sys/class/backlight/nv_backlight gets modified instead of /sys/class/backlight/intel_backlight when I press the backlight buttons, anything I should try before shutting down the live image? adamw >> hadess: halfline: any ideas there? adamw >> (enunes' question) adamw >> enunes: so just to be clear, the intel adapter is driving the display, but the keys seem to be changing the values for the nvidia adapter? enunes >> adamw: that's what I understand from it, yes adamw >> enunes: cool. definitely sounds like a bug, yep. if hadess or halfline aren't around / don't know what to suggest, i'd say at least file a bug with hardware info, description of the issue, and, i dunno, journal log is always a safe bet, maybe the contents of the relevant bits of /sys ... halfline >> probably a upower bug ? halfline >> enunes: what's the output of ls /sys/class/leds | fpaste ? halfline >> oh wait i misunderstood the question halfline >> it's not the keyboard backlight that's broken it's the backlight keys on the keyboard that are broken adamw >> right, they seem to be controlling the wrong thing enunes >> adamw: halfline: http://paste.fedoraproject.org/469817/3749147/ -> https://paste.fedoraproject.org/469817/03749147 halfline >> enunes: can you post udevadm info --export-db | fpaste ? halfline >> the gsd_backlight_helper_get_best_backlight function looks a little dumb enunes >> halfline: http://paste.fedoraproject.org/469820/47820402/ halfline >> enunes: okay and what are the values of cat /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card1/card1-LVDS-2/nv_backlight/type and cat /sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-LVDS-1/intel_backlight/type enunes >> halfline: raw and raw halfline >> right okay, so it's just picking the first one it finds then halfline >> the code should probably look at the parent card and match it to the one currently being used
Version: 3.22.x