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<b><a class="bz_bug_link
bz_status_NEEDINFO "
title="NEEDINFO --- - [snb] initial backlight brightness is zero"
href="https://bugs.freedesktop.org/show_bug.cgi?id=70256#c15">Comment # 15</a>
on <a class="bz_bug_link
bz_status_NEEDINFO "
title="NEEDINFO --- - [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:tkhai@yandex.ru" title="Kirill Tkhai <tkhai@yandex.ru>"> <span class="fn">Kirill Tkhai</span></a>
</span></b>
<pre>(In reply to <a href="show_bug.cgi?id=70256#c13">comment #13</a>)
<span class="quote">> (In reply to <a href="show_bug.cgi?id=70256#c12">comment #12</a>)
> > What if you try the acpi_osi="!Windows 2012" kernel parameter?
>
> Hmm, this was sandy bridge though... have you upgraded your bios? (I am not
> implying you should, I'm merely asking.)</span >
No yet. I'll try to do upgrade too.
(In reply to <a href="show_bug.cgi?id=70256#c14">comment #14</a>)
<span class="quote">> Another module parameter to try: video.use_bios_initial_backlight=0.</span >
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</pre>
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