[Bug 96571] [CHV] Backlight init fails on Surface 3 if module load order is wrong

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=96571

--- Comment #5 from viric at viric.name ---
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. So I don't see how it is a problem of ordering.

http://www.spinics.net/lists/intel-gfx/msg92148.html
-----------------
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 bug 90075 is very well related to this (I also wrote
this text therE). Isn't it?

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