RE: [Nouveau] [PATCH 1/7] Revert "ACPI / OSI: Add OEM _OSI string to enable dGPU direct output"

[Mario.Limonciello]

> -----Original Message-----
> From: linux-acpi-owner@xxxxxxxxxxxxxxx <linux-acpi-owner@xxxxxxxxxxxxxxx> On
> Behalf Of Dave Airlie
> Sent: Wednesday, August 14, 2019 5:48 PM
> To: Karol Herbst
> Cc: LKML; Linux ACPI; dri-devel; nouveau; Rafael J . Wysocki; Alex Hung; Ben
> Skeggs; Dave Airlie
> Subject: Re: [Nouveau] [PATCH 1/7] Revert "ACPI / OSI: Add OEM _OSI string to
> enable dGPU direct output"
> 
> On Thu, 15 Aug 2019 at 07:31, Karol Herbst <kherbst@xxxxxxxxxx> wrote:
> >
> > This reverts commit 28586a51eea666d5531bcaef2f68e4abbd87242c.
> >
> > The original commit message didn't even make sense. AMD _does_ support it and
> > it works with Nouveau as well.
> >
> > Also what was the issue being solved here? No references to any bugs and not
> > even explaining any issue at all isn't the way we do things.
> >
> > And even if it means a muxed design, then the fix is to make it work inside the
> > driver, not adding some hacky workaround through ACPI tricks.
> >
> > And what out of tree drivers do or do not support we don't care one bit anyway.
> >
> 
> I think the reverts should be merged via Rafael's tree as the original
> patches went in via there, and we should get them in asap.
> 
> Acked-by: Dave Airlie <airlied@xxxxxxxxxx>
> Dave.

There are definitely going to be regressions on machines in the field with the
in tree drivers by reverting this.  I think we should have an answer for all of those
before this revert is accepted.

Regarding systems with Intel+NVIDIA, we'll have to work with partners to collect
some information on the impact of reverting this.

When this is used on a system with Intel+AMD the ASL configures AMD GPU to use
"Hybrid Graphics" when on Windows and "Power Express" and "Switchable Graphics"
when on Linux.

I feel we need a knob and/or DMI detection to affect the changes that the ASL
normally performs.