http://bugzilla.opensuse.org/show_bug.cgi?id=1040718 Stefan Dirsch changed: What |Removed |Added ---------------------------------------------------------------------------- Priority|P5 - None |P3 - Medium Status|NEW |CONFIRMED Component|X.Org |X11 3rd Party Driver QA Contact|xorg-maintainer-bugs@forge. |sndirsch@suse.com |provo.novell.com | -- You are receiving this mail because: You are on the CC list for the bug.

http://bugzilla.opensuse.org/show_bug.cgi?id=1040718 http://bugzilla.opensuse.org/show_bug.cgi?id=1040718#c2 --- Comment #2 from Daniel Dadap --- `xrandr --brightness` works by adjusting the brightness of the image as you say, but the Backlight property is supposed to actually adjust the backlight. `xrandr --verbose` should advertise the availability of the backlight property on your display, and list what the range of acceptable values is. Once you know the name of the output CRTC associated with your panel, and the valid range, you should be able to do e.g.: xrandr --output LVDS-0 --set Backlight 10 -- You are receiving this mail because: You are on the CC list for the bug.

http://bugzilla.opensuse.org/show_bug.cgi?id=1040718 http://bugzilla.opensuse.org/show_bug.cgi?id=1040718#c4 --- Comment #4 from Stefan Dirsch --- Thanks a lot for the hints, Daniel! -- You are receiving this mail because: You are on the CC list for the bug.

http://bugzilla.opensuse.org/show_bug.cgi?id=1040718 http://bugzilla.opensuse.org/show_bug.cgi?id=1040718#c6 --- Comment #6 from Daniel Dadap --- Thanks; I don't see the Backlight property listed in your xrandr output. Perhaps Nouveau doesn't expose it, either in general, or on your hardware. I fired up a random laptop with an NVIDIA GPU and confirmed that I don't see the Backlight property when running Nouveau, but I do when running the NVIDIA driver. On this particular system, the valid range is 0-100 on LVDS-0, so the example xrandr command from comment #3 should work verbatim. Here's a snippet from my xrandr output so you can see what it should look like if the Backlight property is properly exposed: LVDS-0 connected primary 1920x1080+0+0 (0x2e0) normal (normal left inverted right x axis y axis) 344mm x 194mm Identifier: 0x2df Timestamp: 740325 Subpixel: unknown Gamma: 1.0:1.0:1.0 Brightness: 1.0 Clones: CRTC: 0 CRTCs: 0 1 2 3 Transform: 1.000000 0.000000 0.000000 0.000000 1.000000 0.000000 0.000000 0.000000 1.000000 filter: _MUTTER_PRESENTATION_OUTPUT: 0 CscMatrix: 65536 0 0 0 0 65536 0 0 0 0 65536 0 Backlight: 10 range: (0, 100) -- You are receiving this mail because: You are on the CC list for the bug.

http://bugzilla.opensuse.org/show_bug.cgi?id=1040718 http://bugzilla.opensuse.org/show_bug.cgi?id=1040718#c8 --- Comment #8 from David Rankin --- Created attachment 726473 --> http://bugzilla.opensuse.org/attachment.cgi?id=726473&action=edit xrandr --verbose with nvidia driver Thank you for the follow-up. I installed the nvidia drivers, e.g. nvidia-computeG04-375.66-22.1.x86_64 nvidia-gfxG04-kmp-default-375.66_k4.4.27_2-22.1.x86_64 nvidia-glG04-375.66-22.1.x86_64 x11-video-nvidiaG04-375.66-22.1.x86_64 The xrandr 'Backlight' is advertised (and I do now have LVDS-0 instead of LVDS-1 present with nouveau). All backlight control through sysfs (e.g. /sys/class/backlight) is lost. $ l /sys/class/backlight/ total 0 drwxr-xr-x 2 root root 0 May 25 22:00 . drwxr-xr-x 55 root root 0 May 25 22:00 .. lrwxrwxrwx 1 root root 0 May 25 22:00 acpi_video0 -> ../../devices/pci0000:00/0000:00:01.0/0000:01:00.0/backlight/ acpi_video0 provides no backlight control at all. (I can set it to any value and it does not change anything) Thankfully, your suggestion of 'xrandr --output LVDS-0 --set Backlight 50' does in fact change the screen brightness. Is this really setting the proper backlight display power output instead of just darkening the pixel brightness? How do we get a sysfs interface back? How would I control the backlight in a console login? I've got the nvidia drivers loaded, so anything you need me to check, I'm happy to do. Thank you for all your help. -- You are receiving this mail because: You are on the CC list for the bug.

http://bugzilla.opensuse.org/show_bug.cgi?id=1040718 Stefan Dirsch changed: What |Removed |Added ---------------------------------------------------------------------------- Assignee|xorg-maintainer-bugs@forge. |sndirsch@suse.com |provo.novell.com | -- You are receiving this mail because: You are on the CC list for the bug.

http://bugzilla.opensuse.org/show_bug.cgi?id=1040718 http://bugzilla.opensuse.org/show_bug.cgi?id=1040718#c11 --- Comment #11 from David Rankin --- kernel-default-4.4.74-18.20.1.x86_64 restored the operation of /sys/class/backlight/acpi_video0/brightness. I now get: $ cat /sys/class/backlight/acpi_video0/max_brightness 20 and $ su -c 'echo 8 > /sys/class/backlight/acpi_video0/brightness' does now set the brightness to 40%. However, I'm confused. The actual 'Backlight' setting with xrandr is unchanged. Recall, as a workaround I had been setting xrandr to manipulate the backlight with $ xrandr --output LVDS-0 --set Backlight $newbl Now both methods affect the Backlight/brightness, but neither reflect changes made be the other. E.g. if I use xrandr set to 60%, then the value in acpi_video0/brightness remains unchanged. (which would be acpi_video0/brightness 12) Conversely, if I set acpi_video0/brightness to 8, xrandr --verbose | sed -n '/Backlight\|Brightness/p' backlight is still 60, but the screen brightness has changed to the 40% level. So they are both doing what they are supposed to do, but changes in one are not reflected in the other (which may be exactly how it is supposed to work) So kudos to whoever got acpi_video0/brightness to actually change the brightness with the nvidia driver installed. If this is working as it should, then this bug can be closed. Let me know if you need more info. I show the following related to nvidia modules: $ lsmod | grep nvidia nvidia_drm 53248 1 nvidia_modeset 790528 4 nvidia_drm nvidia_uvm 684032 0 nvidia 12328960 62 nvidia_modeset,nvidia_uvm drm_kms_helper 155648 1 nvidia_drm drm 393216 4 drm_kms_helper,nvidia_drm -- You are receiving this mail because: You are on the CC list for the bug.

http://bugzilla.opensuse.org/show_bug.cgi?id=1040718 http://bugzilla.opensuse.org/show_bug.cgi?id=1040718#c13 --- Comment #13 from Stefan Dirsch ---

[...] So they are both doing what they are supposed to do, but changes in one are not > reflected in the other (which may be exactly how it is supposed to work) [...] If this is working as it should, then this bug can be closed.

Honestly, I don't know. :-( Daniel may know though for NVIDIA's driver. I guess most people are just happy with backlight control keys working on their laptop, which is probably using /sys/class/backlight/acpi_video0/brightness. -- You are receiving this mail because: You are on the CC list for the bug.