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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_NEEDINFO "
title="NEEDINFO - Brightness control inversion from VBT table is not taken into account in Ubuntu 18.10"
href="https://bugs.freedesktop.org/show_bug.cgi?id=111475">bug 111475</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>NEW
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<td>NEEDINFO
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<b><a class="bz_bug_link
bz_status_NEEDINFO "
title="NEEDINFO - Brightness control inversion from VBT table is not taken into account in Ubuntu 18.10"
href="https://bugs.freedesktop.org/show_bug.cgi?id=111475#c1">Comment # 1</a>
on <a class="bz_bug_link
bz_status_NEEDINFO "
title="NEEDINFO - Brightness control inversion from VBT table is not taken into account in Ubuntu 18.10"
href="https://bugs.freedesktop.org/show_bug.cgi?id=111475">bug 111475</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>We don't look at the VBT active low bit, instead we read the backlight
registers and check what the BIOS has set up. This is due to historical
reasons, we always preferred what was actually set up by the BIOS instead of
looking at the VBT. Arguably this is a bug; if the BIOS does not set up the
registers, we don't get it right.
Does your BIOS enable the display?
Please set drm.debug=14 module parameter, and attach dmesg output all the way
from boot.
Please attach /sys/kernel/debug/dri/0/i915_vbt.</pre>
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