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<b><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - [SNB] KMS with intel sandy bridge video sets brightness to zero."
href="https://bugs.freedesktop.org/show_bug.cgi?id=43577#c51">Comment # 51</a>
on <a class="bz_bug_link
bz_status_NEW "
title="NEW --- - [SNB] KMS with intel sandy bridge video sets brightness to zero."
href="https://bugs.freedesktop.org/show_bug.cgi?id=43577">bug 43577</a>
from <span class="vcard"><a class="email" href="mailto:gustavo@sagui.org" title="Gustavo Vieira <gustavo@sagui.org>"> <span class="fn">Gustavo Vieira</span></a>
</span></b>
<pre>Found the problem and a solution. Apparently it is a BIOS bug where it is
claimed the display uses minimum backlight at boot.
More info: <a href="https://bugzilla.kernel.org/show_bug.cgi?id=21212">https://bugzilla.kernel.org/show_bug.cgi?id=21212</a> and
<a href="https://bugzilla.kernel.org/show_bug.cgi?id=51141">https://bugzilla.kernel.org/show_bug.cgi?id=51141</a>
The solution is to put video.use_bios_initial_backlight=0 in the kernel command
line. A more definitive fix is to add this laptop to a white list of machines
needing this parameter. I've made a patch to fix it and have sent it to the
ACPI list: <a href="http://www.spinics.net/lists/linux-acpi/msg42467.html">http://www.spinics.net/lists/linux-acpi/msg42467.html</a></pre>
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