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<base href="https://bugs.freedesktop.org/" />
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<body><table border="1" cellspacing="0" cellpadding="8">
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<th>Priority</th>
<td>medium
</td>
</tr>
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Brightness adjustment is broken in 945GM with kernel 3.14-rc2"
href="https://bugs.freedesktop.org/show_bug.cgi?id=75001">75001</a>
</td>
</tr>
<tr>
<th>CC</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
</tr>
<tr>
<th>Assignee</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
</tr>
<tr>
<th>Summary</th>
<td>Brightness adjustment is broken in 945GM with kernel 3.14-rc2
</td>
</tr>
<tr>
<th>QA Contact</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux (All)
</td>
</tr>
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<th>Reporter</th>
<td>luiorpe1@gmail.com
</td>
</tr>
<tr>
<th>Hardware</th>
<td>x86 (IA32)
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Version</th>
<td>XOrg CVS
</td>
</tr>
<tr>
<th>Component</th>
<td>DRM/Intel
</td>
</tr>
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<th>Product</th>
<td>DRI
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=94098" name="attach_94098" title="dmesg output 3.14-rc2 with drm.debug">attachment 94098</a> <a href="attachment.cgi?id=94098&action=edit" title="dmesg output 3.14-rc2 with drm.debug">[details]</a></span>
dmesg output 3.14-rc2 with drm.debug
First reported in the Linux kernel mailing list.
Laptop Model: Asus EeePC 1000H
Graphics: Intel 945GM
Testing the kernel version 3.14-rc2 I noticed adjusting the screen brightness
didn't work. The problem is already present in 3.14-rc1 whereas the 3.13 branch
works fine.
I first bisected the issue down to the following commit:
bc0bb9fd1c7810407ab810d204bbaecb255fddde drm/i915: remove
QUIRK_NO_PCH_PWM_ENABLE
However, given the concern that the bisection might be bogus I replayed it up
to the last 6 bisect steps. The issue was present in this bisect session and
this time I tracked it down to the commit:
b35684b8fa94e04f55fd38bf672b737741d2f9e2 drm/i915: do full backlight setup at
enable time
Hopefully this makes more sense.
Per request of the developers I've tested changing the brightness manually
through the sysfs. Here are the results.
ls -l /sys/class/backlight:
lrwxrwxrwx 1 root root 0 Feb 14 21:00 eeepc ->
../../devices/platform/eeepc/backlight/eeepc
lrwxrwxrwx 1 root root 0 Feb 14 20:59 intel_backlight ->
../../devices/pci0000:00/0000:00:02.0/drm/card0/card0-LVDS-1/intel_backlight
Linux 3.13.3: change the brightness manually:
Changing /sys/class/backlight/eeepc/brightness changes brightness and updates
the value.
changing /sys/class/backlight/intel_backlight/brightness changes brightness but
does NOT update the value. Always reports 156.
Linux 3.14-rc2: change the brightness manually:
changing /sys/class/backlight/eeepc/brightness does NOT change brightness but
updates the value.
changing /sys/class/backlight/intel_backlight/brightness changes brightness and
updates the value.
Finally I attach the following files:
dmesg.log</pre>
</div>
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