Re: [Nouveau] [PATCH v2] ALSA: hda: Continue to probe when codec probe fails

[Roy Spliet]

Op 10-04-2021 om 20:23 schreef Lukas Wunner:
> On Sat, Apr 10, 2021 at 04:51:27PM +0100, Roy Spliet wrote:
> > Can I ask someone with more
> > technical knowledge of snd_hda_intel and vgaswitcheroo to brainstorm about
> > the possible challenges of nouveau taking matters into its own hand rather
> > than keeping this PCI quirk around?
>
> It sounds to me like the HDA is not powered if no cable is plugged in.
> What is reponsible then for powering it up or down, firmware code on
> the GPU or in the host's BIOS?

Sometimes the BIOS, but definitely unconditionally the PCI quirk code: 
https://github.com/torvalds/linux/blob/master/drivers/pci/quirks.c#L5289

(CC Aaron Plattner)

> Ideally, we should try to find out how to control HDA power from the
> operating system rather than trying to cooperate with whatever firmware
> is doing.  If we have that capability, the OS should power the HDA up
> and down as it sees fit.
>
> Thanks,
>
> Lukas