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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 --- - [i915] backlight issue on TOSHIBA PORTEGE R830 after suspend/resume"
href="https://bugs.freedesktop.org/show_bug.cgi?id=82634">82634</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>[i915] backlight issue on TOSHIBA PORTEGE R830 after suspend/resume
</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>
<tr>
<th>Reporter</th>
<td>sylvain.pasche@gmail.com
</td>
</tr>
<tr>
<th>Hardware</th>
<td>x86-64 (AMD64)
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
<tr>
<th>Component</th>
<td>DRM/Intel
</td>
</tr>
<tr>
<th>Product</th>
<td>DRI
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=104639" name="attach_104639" title="kernel 3.16 dmesg">attachment 104639</a> <a href="attachment.cgi?id=104639&action=edit" title="kernel 3.16 dmesg">[details]</a></span>
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
<a href="https://bugzilla.redhat.com/show_bug.cgi?id=1126159">https://bugzilla.redhat.com/show_bug.cgi?id=1126159</a>
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.</pre>
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