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

[Takashi Iwai]

On Thu, 15 Aug 2019 16:37:05 +0200,
Alex Deucher wrote:
> 
> On Thu, Aug 15, 2019 at 10:25 AM Karol Herbst <kherbst@xxxxxxxxxx> wrote:
> >
> > On Thu, Aug 15, 2019 at 4:20 PM <Mario.Limonciello@xxxxxxxx> wrote:
> > >
> > > > > 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.
> > > >
> > > > and what's exactly the difference between those? And what's the actual
> > > > issue here?
> > >
> > > DP/HDMI is not detected unless plugged in at bootup.  It's due to missing HPD
> > > events.
> > >
> >
> > afaik Lyude was working on fixing all that, at least for some drivers.
> > If there is something wrong, we still should fix the drivers, not
> > adding ACPI workarounds.
> >
> > Alex: do you know if there are remaining issues regarding that with amdgpu?
> 
> There was an issue with hpd events not making it to the audio side
> when things were powered down that was fixed with this patch set:
> https://patchwork.freedesktop.org/patch/316793/
> Those patches depended on a bunch of alsa changes as well which may
> have not been available in the distro used for a particular OEM
> program.

FYI, the corresponding commit for ALSA part is destined for 5.4
kernel: 
  https://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git/commit/?id=ade49db337a9d44ac5835cfce1ee873549011b27

BTW, Nouveau should suffer from the same problem.  The patch to add
the audio component support is found at:
  https://patchwork.freedesktop.org/patch/319131/


thanks,

Takashi