[Bug 82634] New: [i915] backlight issue on TOSHIBA PORTEGE R830 after suspend/resume
bugzilla-daemon at freedesktop.org
bugzilla-daemon at freedesktop.org
Thu Aug 14 14:54:56 PDT 2014
https://bugs.freedesktop.org/show_bug.cgi?id=82634
Priority: medium
Bug ID: 82634
CC: intel-gfx-bugs at lists.freedesktop.org
Assignee: intel-gfx-bugs at lists.freedesktop.org
Summary: [i915] backlight issue on TOSHIBA PORTEGE R830 after
suspend/resume
QA Contact: intel-gfx-bugs at lists.freedesktop.org
Severity: normal
Classification: Unclassified
OS: Linux (All)
Reporter: sylvain.pasche at gmail.com
Hardware: x86-64 (AMD64)
Status: NEW
Version: unspecified
Component: DRM/Intel
Product: DRI
Created attachment 104639
--> https://bugs.freedesktop.org/attachment.cgi?id=104639&action=edit
kernel 3.16 dmesg
I experienced issues with the backlight adjustment after installing Fedora on a
TOSHIBA PORTEGE R830 laptop.
The full detail of the issue is available on
https://bugzilla.redhat.com/show_bug.cgi?id=1126159
To summarize: after booting the Fedora 21 kernel (3.16), 3 backlight interfaces
are available (acpi_video0, intel_backlight, toshiba).
The acpi_video0 and toshiba interfaces are not working after suspend/resume.
Only the intel_backlight can change the backlight value after resume.
Red Hat engineer Hans de Goede suggested as a fix to disable the acpi_video0
and toshiba at the kernel level to keep only the intel_backlight. He built a
patched kernel with that change, but that change keeps the backlight unlit
after suspend/resume (and changing the backlight value through sysfs has no
effect).
So he suggested I open a bug on the Intel driver here.
I did the following tests with the result files in attachment.
1) Boot the Fedora 21 3.16.0 kernel (without X) with drm.debug=0x06
- do a register intel_reg_dump before suspend
(intel_reg_dump_before_3.16.0-1.fc21.x86_64.txt)
- suspend/resume, then dump the registers again
(intel_reg_dump_after_3.16.0-1.fc21.x86_64.txt)
- demsg: dmesg_3.16.0-1.fc21.x86_64.txt
In this case, the backlight is working after suspend / resume (through the
intel interface).
2) Boot the Fedora kernel patched by Hans with a change to disable the
acpi_video0 and toshiba backlight interfaces.
- register dump before suspend:
intel_reg_dump_before_3.15.9-200.rhbz1126159.fc20.x86_64.txt
- register dump after resume:
intel_reg_dump_after_3.15.9-200.rhbz1126159.fc20.x86_64.txt
- dmesg: dmesg_3.15.9-200.rhbz1126159.fc20.x86_64.txt
In this case, the backlight is black after resuming.
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