https://bugzilla.kernel.org/show_bug.cgi?id=91191
--- Comment #7 from EmanueL Czirai <[email protected]> --- Created attachment 163581 --> https://bugzilla.kernel.org/attachment.cgi?id=163581&action=edit current Xorg.0.log I don't see any mention of backlight in Xorg.0.log but I am including it here. In dmesg however I see something(radeon atom DIG backlight ?) which I paste here: [ 0.197848] device class 'backlight': registering [ 1.360959] [drm] radeon atom DIG backlight initialized [ 11.922760] systemd[1]: Starting system-systemd\x2dbacklight.slice. [ 11.961366] systemd[1]: Created slice system-systemd\x2dbacklight.slice. [ 11.981589] systemd[1]: Starting Load/Save Screen Backlight Brightness of backlight:acpi_video0... [ 12.017303] systemd[1]: Starting Load/Save Screen Backlight Brightness of backlight:radeon_bl0... [ 12.073454] systemd[1]: Started Load/Save Screen Backlight Brightness of backlight:acpi_video0. [ 12.108095] systemd[1]: Started Load/Save Screen Backlight Brightness of backlight:radeon_bl0. [ 15.961722] thinkpad_acpi: Standard ACPI backlight interface available, not loading native one [ 24.992104] pkexec[3949]: emacs: Executing command [USER=root] [TTY=unknown] [CWD=/] [COMMAND=/usr/bin/xfpm-power-backlight-helper --set-brightness-switch 0] [ 34.757180] pkexec[3991]: emacs: Executing command [USER=root] [TTY=unknown] [CWD=/] [COMMAND=/usr/bin/xfpm-power-backlight-helper --set-brightness-switch 1] [ 37.797145] pkexec[4133]: emacs: Executing command [USER=root] [TTY=unknown] [CWD=/] [COMMAND=/usr/bin/xfpm-power-backlight-helper --set-brightness-switch 0] Interestingly changing brightness as you noted, doesn't generate the errors: # cd /sys/class/backlight/radeon_bl0/ # cat max_brightness 255 # echo "200" > brightness # cat brightness 200 The brightness was visibly changed, however no errors on dmesg|tail . Now, there's another brightness which DOES generate the error: # cd /sys/class/backlight/acpi_video0 # echo '9' > brightness # dmesg|tail ... [24951.307524] APIC error on CPU0: 80 : Illegal register address (the brightness is visibly changed and affected though) even setting the same value: 9 generates a new error: # echo '9' > brightness ... [24951.307524] APIC error on CPU0: 80 : Illegal register address [24990.043742] APIC error on CPU0: 80 : Illegal register address Also the acpi_video0/brightness and radeon_bl0/brightness are not sync-ed: if you set one, the other remains as it is, even though both have visible effect on the brightness. I guess this makes some sense. I guess to answer your question, seems that X uses acpi_video0 (10 steps - check; acpi error - check) Thank. -- You are receiving this mail because: You are watching the assignee of the bug. ------------------------------------------------------------------------------ New Year. New Location. New Benefits. New Data Center in Ashburn, VA. GigeNET is offering a free month of service with a new server in Ashburn. Choose from 2 high performing configs, both with 100TB of bandwidth. Higher redundancy.Lower latency.Increased capacity.Completely compliant. http://p.sf.net/sfu/gigenet _______________________________________________ acpi-bugzilla mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/acpi-bugzilla
