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<b><a class="bz_bug_link
bz_status_NEW "
title="NEW - [LPT SPT KBP] Acer V3-772G screen brightness cannot be adjusted with i915.fastboot enabled"
href="https://bugs.freedesktop.org/show_bug.cgi?id=108225#c22">Comment # 22</a>
on <a class="bz_bug_link
bz_status_NEW "
title="NEW - [LPT SPT KBP] Acer V3-772G screen brightness cannot be adjusted with i915.fastboot enabled"
href="https://bugs.freedesktop.org/show_bug.cgi?id=108225">bug 108225</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 Tolga Cakir from <a href="show_bug.cgi?id=108225#c21">comment #21</a>)
<span class="quote">> I have exactly the same issue on the Dell M3800 (Intel i7-4702HQ + muxless
> Nvidia K1100M). Using i915.fastboot=1, I don't see a single flicker from
> power-on all the way to GNOME desktop. However, just as reported, backlight
> control doesn't work and is set to maximum. I have additionally tried
> acpi_backlight=[vendor,native,video] without any success.
>
> I can test patches and provide further debug infos, if needed. Please let me
> know.</span >
Do you have LynxPoint (LPT) PCH? Look for something like this in the dmesg:
[ 5.224781] [drm:intel_pch_type [i915]] Found LynxPoint PCH
Does the trick from <a href="show_bug.cgi?id=108225#c12">comment #12</a> help? What's the output of the intel_reg reads
in the two scenarios? (See <a href="show_bug.cgi?id=108225#c13">comment #13</a> for example.)
I just want to ensure you are really experiencing the same bug, and not
something else.</pre>
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