Bug 30063 - [bisected] start X will modify brightness value to zero
Summary: [bisected] start X will modify brightness value to zero
Status: VERIFIED FIXED
Alias: None
Product: xorg
Classification: Unclassified
Component: Driver/intel (show other bugs)
Version: unspecified
Hardware: All Linux (All)
: medium major
Assignee: Carl Worth
QA Contact: Xorg Project Team
URL:
Whiteboard:
Keywords:
Depends on:
Blocks:
 
Reported: 2010-09-07 04:04 UTC by fangxun
Modified: 2010-09-08 21:37 UTC (History)
0 users

See Also:
i915 platform:
i915 features:

Attachments
Xorg log file (21.81 KB, text/plain)
2010-09-07 04:04 UTC, fangxun 		no flags Details
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Description fangxun 2010-09-07 04:04:55 UTC 
Created attachment 38505 [details]
Xorg log file

System Environment:
--------------------------
Arch:           i386
Platform:       pineview
Libdrm:         (master)2.4.21-18-g23287f05cf2443ddf9e028e29beb5bd30979c6cf
Mesa:           (master)35e01b79cb576503fc6c7cd5759b379c26ecb5ee
Xserver:        (master)xorg-server-1.9.0
Xf86_video_intel: (master)2.12.0-78-g00f6af2c8ec899258ffab60dc2d9d80c4d9daec8
Kernel: (for-linus)76be97c1fc945db08aae1f1b746012662d643e97


Bug detailed description:
-------------------------
Brightness value is non-zero value before start X. The value will be modified to zero after start X. Bisect find it is Xf86_video_intel component causes the problem. 38f940dfea494d3093236f065392c431be06ae6e is the first bad commit.
commit 38f940dfea494d3093236f065392c431be06ae6e
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Wed Aug 4 09:50:14 2010 +0100

    display: Tidy backlight initialisation

    Mostly whitespace and a single error-code fix.

    Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>


Reproduce steps:
----------------
1. start X
2. cat /sys/class/backlight/acpi_video0/brightness
Comment 1 Chris Wilson 2010-09-07 04:33:32 UTC 
Can you confirm that a "git revert 38f940dfea494d3093236f065392c431be06ae6e" fixes the problem?
Comment 2 Chris Wilson 2010-09-07 04:58:44 UTC 
commit 273d34fbc43e54a8539fbe7efc1dca66bbb4e6dc
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Tue Sep 7 12:57:04 2010 +0100

    display: Query current level after finding max value.
    
    The current backlight value is clamped to the valid range [0, max] and
    so as we queried the value before setting the max, we forced the current
    backlight to 0 and so set it to be zero on initialising the display.
    
    Fixes:
    
      Bug 30063 - start X will modify brightness value to zero
      https://bugs.freedesktop.org/show_bug.cgi?id=30063
    
    which is a regression due to 38f940dfea494d3093236f065392c431be06ae6e.
    
    Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Comment 3 fangxun 2010-09-08 21:37:04 UTC 
It works fine with the fixed commit. Thanks Chris.

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