Bug 909737

Summary: Lenovo T430s: ACPI backlight controls broken since kernel 3.7
Product: [Fedora] Fedora Reporter: Gordon Messmer <gordon.messmer>
Component: kernelAssignee: Kernel Maintainer List <kernel-maint>
Status: CLOSED DUPLICATE QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: 18CC: crobinso, gansalmon, gcase, itamar, jonathan, kernel-maint, maciek.borzecki, madhu.chinakonda
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Fixed In Version: Doc Type: Bug Fix
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Last Closed: 2013-04-12 16:22:28 UTC Type: Bug
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description Gordon Messmer 2013-02-10 19:50:55 UTC 
Description of problem:
Under both 3.6 kernels built for f18, keyboard brightness controls work normally.  The screen brightness changes, the OSD reflects the correct level, and the content of /sys/class/backlight/acpi_video0/brightness will reflect a value between 0 and 15.

Under all of the 3.7 kernels that I've tested, the system's behavior is odd.  From the default, full brightness, the keyboard will step brightness down only once.  The OSD will show the correct current value.  The content of /sys/class/backlight/acpi_video0/brightness now ranges from 0 to 100 instead of 0 and 15, though the keyboard can only step down to 95 from 100, and back.

Under the same kernels, the GNOME brightness control center app can adjust brightness along the full scale of 0 to 100.  If the brightness is set to a value between 75 and 15, the keyboard controls can be used to step the brightness up and down within that range.

Finally, if I boot the kernel with the additional arg "acpi_backlight=vendor" under 3.7, the keyboard controls work somewhat better.  The screen brightness will change normally on keyboard presses.  However, /sys/class/backlight/acpi_video0/brightness will contain only either 0 or 1, so the OSD will indicate only one of those two values.

Version-Release number of selected component (if applicable):
kernel-3.7.1-2.fc18
kernel-3.7.4-204.fc18.x86_64
kernel-3.7.5-201.fc18.x86_64
kernel-3.7.6-201.fc18.x86_64
Comment 1 Cole Robinson 2013-02-24 14:12:51 UTC 
*** Bug 903746 has been marked as a duplicate of this bug. ***
Comment 2 Maciek Borzecki 2013-04-03 20:07:20 UTC 
I'm observing similar issue on T430 with 3.8.5. I have confirmed that:
- echo <val> > /sys/class/backlight/acpi_video0/brigthness works for any value in range 0-100
- xbacklight -inc/-dec works
- /usr/libexec/gsd-backlight-helper works, even setting max brigthness or any other value

What does not work is Fn+F8, Fn+F9 keys. If current brigthness is within 15-75 range, the keys work. However it's not possible to get values outside of this range using function keys. If current brightness is outside of 15-75 range, function keys have no effect.
Comment 3 Josh Boyer 2013-04-12 16:22:28 UTC 

*** This bug has been marked as a duplicate of bug 903136 ***