Bug 198907

Summary: Backlight control missing with /sys/class/backlight/ empty
Product: Drivers Reporter: Andrew (aun.sokolov)
Component: Video(DRI - non Intel)Assignee: drivers_video-dri
Status: RESOLVED OBSOLETE    
Severity: normal CC: m.linsmayer, rui.zhang
Priority: P1    
Hardware: Intel   
OS: Linux   
Kernel Version: 4.14.0-3-amd64 #1 SMP Debian 4.14.13-1 (2018-01-14) x86_64 GNU/Linux Subsystem:
Regression: No Bisected commit-id:
Attachments: dmesg with drm.debug=14 added

Description Andrew 2018-02-23 19:46:09 UTC 
Laptop HP Omen 15-ce012ur 
4.14.0-3-amd64 #1 SMP Debian 4.14.13-1 (2018-01-14) x86_64 GNU/Linux.


My video card shows in lspci as:

01:00.0 VGA compatible controller: NVIDIA Corporation GP106M [GeForce GTX 1060] (rev a1).


Freshly installed Debian. While loading, shows numerous copies of "ACPI Error: namespace lookup failure. AE_NOT_FOUND".
/sys/class/backlight/ was empty from the start, all ways of changing brightness do not exist. 
That also holds for live-USB with Debian and Ubuntu as well.
Comment 1 Zhang Rui 2018-03-12 07:12:13 UTC 
reassign to the graphics experts
Comment 2 Jani Nikula 2018-03-19 08:33:32 UTC 
Please attach dmesg with drm.debug=14 added.
Comment 3 Andrew 2018-03-22 10:58:30 UTC 
Created attachment 274865 [details]
dmesg with drm.debug=14 added
Comment 4 Andrew 2018-03-22 10:58:50 UTC 
(In reply to Jani Nikula from comment #2)
> Please attach dmesg with drm.debug=14 added.

done
Comment 5 Jani Nikula 2018-04-11 15:09:29 UTC 
[    6.112689] nvidia: loading out-of-tree module taints kernel.
[    6.112708] nvidia: module license 'NVIDIA' taints kernel.
Comment 6 Manuel 2018-04-28 07:53:24 UTC 
Hello!

I have a very similar situation, in my opinion. I'm running kernel 4.15.0-20, my distro is Kubuntu 18.04, my hardware is a Dell XPS 15 9560 running with latest firmware (1.9.4) in UEFI mode.

/sys/class/backlight is also empty for me. I have an Intel 591B as well as an discrete NVIDIA GeForce GTX 1050. Situation is the same, no matter whether I'm using Intel or NVIDIA graphics.

I'm also getting ACPI errors at startup.

[    0.000000] ACPI: Core revision 20170831
[    0.000000] ACPI Error: [\_SB_.PCI0.XHC_.RHUB.HS11] Namespace lookup failure, AE_NOT_FOUND (20170831/dswload-210)
[    0.000000] ACPI Exception: AE_NOT_FOUND, During name lookup/catalog (20170831/psobject-252)
[    0.000000] ACPI Exception: AE_NOT_FOUND, (SSDT:xh_rvp11) while loading table (20170831/tbxfload-228)
[    0.000000] ACPI Error: 1 table load failures, 12 successful (20170831/tbxfload-246)

I'm able to see ACPI events when pressing brightness down/up buttons:

 9DBB5994-A997-11� 000000d0 00000000
video/brightnessdown BRTDN 00000087 00000000 K
 9DBB5994-A997-11� 000000d0 00000000
video/brightnessup BRTUP 00000086 00000000 K

I played around with acpi_osi and acpi_backlight, but this doesn't change anything.

Manuel
Comment 7 Jani Nikula 2023-05-26 14:27:31 UTC 
Closing this ancient bug. Please file a new bug at https://gitlab.freedesktop.org/drm/intel/wikis/How-to-file-i915-bugs if still relevant.