[Intel-gfx] Fixing i915/opregion issues with firmware which lists more then 8 output devices

[Hans de Goede]

Hi,

As discussed in the past, the i915 opregion code does not do the
right thing wrt the CADL field when there are more then 8 outputs,
this is causing issues on many different types of Asus laptops.

This thread has details and a number of attempts to fix this:

https://lkml.org/lkml/2014/2/11/1032

This is impacting many users, here is an incomplete list of bug reports:

https://bugzilla.kernel.org/show_bug.cgi?id=70241
https://bugzilla.kernel.org/show_bug.cgi?id=88941
https://bugzilla.redhat.com/show_bug.cgi?id=1144866
https://bugzilla.redhat.com/show_bug.cgi?id=1277785

And I'm pretty sure that is just the tip of the iceberg, some users
have even analyzed their BIOS AML code and come up with an AML
hack in an attempt to fix this:

http://blog.yjwong.name/fixing-display-backlight-hotkeys-on-asus-n550jk/

It would be really great of someone from Intel could step up and start
working on a proper fix for this.

Regards,

Hans