<html>
<head>
<base href="https://bugs.freedesktop.org/">
</head>
<body>
<p>
<div>
<b><a class="bz_bug_link
bz_status_NEEDINFO "
title="NEEDINFO - [BYT LPSS backlight] Acer Aspire Switch 10 backlight control"
href="https://bugs.freedesktop.org/show_bug.cgi?id=90075#c11">Comment # 11</a>
on <a class="bz_bug_link
bz_status_NEEDINFO "
title="NEEDINFO - [BYT LPSS backlight] Acer Aspire Switch 10 backlight control"
href="https://bugs.freedesktop.org/show_bug.cgi?id=90075">bug 90075</a>
from <span class="vcard"><a class="email" href="mailto:viric@viric.name" title="viric@viric.name">viric@viric.name</a>
</span></b>
<pre>I think that regarding pwm backlight on x86_64 and these patches from Shobit,
it still applies what I wrote months ago in the mailing list (text copied
below). There is no code at all to use an lpss pwm as backlight in a normal
ACPI x86 kernel.
<a href="http://www.spinics.net/lists/intel-gfx/msg92148.html">http://www.spinics.net/lists/intel-gfx/msg92148.html</a>
-----------------
I think there is a lot to be done first, to be able to test this.
If I understand correctly, despite the lpss pwm may be available, it will
not be used as pwm-backlight (video/backlight/pwm_bl.c) because it depends
on "CONFIG_OF" and it is ready for devicetree only.
The only x86 that enable OF are X86_INTEL_CE and OLPC, and pwm_bl is
completely disabled without OF. I don't have any INTEL_CE or OLPC, this
LPSS of the Atom SoC is a different thing.
So, someone has to implement pwm_bl on my x86 first, for any of the
patches wrt i915 to be used at all. Should X86_INTEL_LPSS enable OF?
Should there be a devicetree definition for it first? Does someone have to
allow pwm_bl to work with ACPI? Is all that ready in some branch of some
other linux team?
--------------------
By the way, I think that <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - [BYT DSI PMIC backlight] Backlight support for Dell Venue 8 Pro"
href="show_bug.cgi?id=85977">bug 85977</a> and <a class="bz_bug_link
bz_status_NEW "
title="NEW - [CHV] Backlight init fails on Surface 3 if module load order is wrong"
href="show_bug.cgi?id=96571">bug 96571</a> are very well related to this.
Isn't it?</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are the assignee for the bug.</li>
<li>You are the QA Contact for the bug.</li>
<li>You are on the CC list for the bug.</li>
</ul>
</body>
</html>