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<b><a class="bz_bug_link
bz_status_NEEDINFO "
title="NEEDINFO --- - Backlight control broken on Dell XPS M1330 w/ kernel >= 3.14.1"
href="https://bugs.freedesktop.org/show_bug.cgi?id=78653#c4">Comment # 4</a>
on <a class="bz_bug_link
bz_status_NEEDINFO "
title="NEEDINFO --- - Backlight control broken on Dell XPS M1330 w/ kernel >= 3.14.1"
href="https://bugs.freedesktop.org/show_bug.cgi?id=78653">bug 78653</a>
from <span class="vcard"><a class="email" href="mailto:mikkeloscar@gmail.com" title="Mikkel Oscar Lyderik <mikkeloscar@gmail.com>"> <span class="fn">Mikkel Oscar Lyderik</span></a>
</span></b>
<pre>(In reply to <a href="show_bug.cgi?id=78653#c3">comment #3</a>)
<span class="quote">> (In reply to <a href="show_bug.cgi?id=78653#c2">comment #2</a>)
> > I finally got some time to do a bit of debugging.
> >
> > Applying this hack: <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - Backlight control broken on Dell XPS13 w/ kernel 3.14-rc7"
href="show_bug.cgi?id=76276#c15">https://bugs.freedesktop.org/show_bug.cgi?id=76276#c15</a>
> > and only this (to 3.15-rc6) solves the problem for me.
>
> And backlight control works with that? What do you have in
> /sys/class/backlight?
>
> The VBT says we should register backlight for that, but then it doesn't
> work. Hmm.</span >
Yeah I don't have intel_backlight there.
with kernel 3.15-rc6 and the hack applied I have:
$ ls -l /sys/class/backlight/
total 0
lrwxrwxrwx 1 root root 0 May 27 16:42 acpi_video0 ->
../../devices/pci0000:00/0000:00:02.0/backlight/acpi_video0
With kernel 3.13.8 (before regression) I have:
$ ls -l
total 0
lrwxrwxrwx 1 root root 0 May 27 16:44 acpi_video0 ->
../../devices/pci0000:00/0000:00:02.0/backlight/acpi_video0
lrwxrwxrwx 1 root root 0 May 27 16:44 intel_backlight ->
../../devices/pci0000:00/0000:00:02.0/drm/card0/card0-LVDS-1/intel_backlight
Backlight control (Fn+ArrowUp/Down) works on both of those setups, but it
breaks when the 3.15-rc6+hack kernel is suspended and woken up again.
Do you need any other infomation?</pre>
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