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<body><span class="vcard"><a class="email" href="mailto:jani.nikula@intel.com" title="Jani Nikula <jani.nikula@intel.com>"> <span class="fn">Jani Nikula</span></a>
</span> changed
<a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED NOTOURBUG - [snb] initial backlight brightness is zero"
href="https://bugs.freedesktop.org/show_bug.cgi?id=70256">bug 70256</a>
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<th>What</th>
<th>Removed</th>
<th>Added</th>
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<td style="text-align:right;">Status</td>
<td>NEEDINFO
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<td>RESOLVED
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<td style="text-align:right;">Resolution</td>
<td>---
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<td>NOTOURBUG
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<td style="text-align:right;">CC</td>
<td>
</td>
<td>aaron.lu@intel.com
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<b><a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED NOTOURBUG - [snb] initial backlight brightness is zero"
href="https://bugs.freedesktop.org/show_bug.cgi?id=70256#c16">Comment # 16</a>
on <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED NOTOURBUG - [snb] initial backlight brightness is zero"
href="https://bugs.freedesktop.org/show_bug.cgi?id=70256">bug 70256</a>
from <span class="vcard"><a class="email" href="mailto:jani.nikula@intel.com" title="Jani Nikula <jani.nikula@intel.com>"> <span class="fn">Jani Nikula</span></a>
</span></b>
<pre>(In reply to <a href="show_bug.cgi?id=70256#c15">comment #15</a>)
<span class="quote">> (In reply to <a href="show_bug.cgi?id=70256#c13">comment #13</a>)
> > Hmm, this was sandy bridge though... have you upgraded your bios? (I am not
> > implying you should, I'm merely asking.)
>
> No yet. I'll try to do upgrade too.</span >
Please don't. That may lead to more problems.
<span class="quote">> (In reply to <a href="show_bug.cgi?id=70256#c14">comment #14</a>)
> > Another module parameter to try: video.use_bios_initial_backlight=0.
>
> Thanks a lot! This solves the problem. Initial values are maximum:
>
> $ cat /sys/class/backlight/acpi_video0/brightness
> 100
>
> $ cat /sys/class/backlight/intel_backlight/brightness
> 4845</span >
Cool! Closing as NOTOURBUG.
Please file a new bug on Power-Video component at the kernel.org bugzilla [1].
Reference this bug and that video.use_bios_initial_backlight=0 fixes the issue,
and attach output of 'dmidecode' there.
[1] <a href="https://bugzilla.kernel.org/enter_bug.cgi?product=ACPI">https://bugzilla.kernel.org/enter_bug.cgi?product=ACPI</a></pre>
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