[Nouveau] [Bug 75985] [NVC1] HDMI audio device only visible after rescan

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=75985

--- Comment #79 from Daniel Drake <dan at reactivated.net> ---
Thanks, you're right, the value changes based on HDMI connector status.

So for this platform, \_SB.PCI0.PEG0 has a PG00 PowerResource that will set the
magic bit in _ON, and likewise \_SB.PCI0.PEG0.PEGP has a _PS0 that will set the
bit too.

This all sounds like it should set the appropriate state at boot time, but I
wouldn't expect these methods to be called when the HDMI connector is
hotplugged. And I can't see any linkage to anything more dynamic like _DSM.

Indeed booting Linux with HDMI already connected, the HDMI audio PCI device
appears. Same on Windows, testing without the nvidia driver installed.

I used the Clover UEFI bootloader to boot windows with a custom DSDT, modified
the GGIV() function to always return zero (disconnected) for this GPIO. Then
booting Windows with HDMI connected, the PCI device no longer appears.

Then I installed the Nvidia windows driver. Connecting HDMI either at boot or
later, the HDMI audio device appears on the PCI bus.

Conclusion: The nvidia windows driver directly controls the magic bit here,
triggering a PCI bus rescan too, without relying on ACPI.

-- 
You are receiving this mail because:
You are the assignee for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/nouveau/attachments/20190624/7dbb3c47/attachment.html>