Bug 43053 - [i915GM][LCD backlight][Regression] Blanking a screen permanently disables LCD backlight
Summary: [i915GM][LCD backlight][Regression] Blanking a screen permanently disables LC...
Status: CLOSED INVALID
Alias: None
Product: DRI
Classification: Unclassified
Component: DRM/Intel (show other bugs)
Version: unspecified
Hardware: x86 (IA32) Linux (All)
: medium normal
Assignee: Daniel Vetter
QA Contact:
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Keywords:
Depends on:
Blocks: 42991 44622
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Reported: 2011-11-17 21:33 UTC by Artem Anisimov
Modified: 2017-07-24 23:03 UTC (History)
4 users (show)

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i915 platform:
i915 features:


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Description Artem Anisimov 2011-11-17 21:33:41 UTC
After upgrading to Linux 3.1.1 I discovered that blanking a screen (e.g., due to inactivity) permanently disables the LCD backlight of my laptop: after the screen is blanked, I can not change its brightness via brightness adjustement keys (these keys work before blanking); a reboot is needed to make the screen bright again. The bug is not present in Linux 3.0.9.

Here is some info about my configuration:

00:02.0 VGA compatible controller: Intel Corporation Mobile 915GM/GMS/910GML Express Graphics Controller (rev 04) (prog-if 00 [VGA controller])
        Subsystem: ASUSTeK Computer Inc. Device 1882
        Flags: bus master, fast devsel, latency 0, IRQ 16
        Memory at feb80000 (32-bit, non-prefetchable) [size=512K]
        I/O ports at ec00 [size=8]
        Memory at d0000000 (32-bit, prefetchable) [size=256M]
        Memory at feb40000 (32-bit, non-prefetchable) [size=256K]
        Expansion ROM at <unassigned> [disabled]
        Capabilities: [d0] Power Management version 2
        Kernel driver in use: i915

00:02.1 Display controller: Intel Corporation Mobile 915GM/GMS/910GML Express Graphics Controller (rev 04)
        Subsystem: ASUSTeK Computer Inc. Device 1882
        Flags: bus master, fast devsel, latency 0
        Memory at fea80000 (32-bit, non-prefetchable) [size=512K]
        Capabilities: [d0] Power Management version 2

uname -a: Linux vault13 3.1.1 #1 PREEMPT Mon Nov 14 10:10:21 MSK 2011 i686 Intel(R) Pentium(R) M processor 2.00GHz GenuineIntel GNU/Linux

Versions of:
 * xf86-video-intel: 2.15,
 * Xserver: 1.9.4,
 * libdrm: 2.4.25,
 * Mesa: 7.10.2.
Comment 1 Artem Anisimov 2011-11-28 22:28:33 UTC
Checked with 3.1.3. Still doesn't work.
Comment 2 Daniel Vetter 2012-04-14 09:59:36 UTC
Given that this is a regression, can you try to bisect this?

Also, please boot with drm.debug=0xe added to the kernel cmdline and grab the dmesg from both the broken and the working kernel (after once blanking the screen).

Also, please test whether the latest kernel (preferrably the latest 3.4-rc) works any better.

Depending upon the results, there's more to gather. But the bisect is usually excellent information for fixing a regression.
Comment 3 Daniel Vetter 2012-06-11 09:37:55 UTC
Hm, reporters seems to have disappeared, closing as unreproducible. Please reopen if this is still an issue for you (with the request logfiles attached, please).


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