sub function power management (gpu + audio device)

[Takashi Iwai]

At Tue, 12 Mar 2013 16:05:26 +1000,
Dave Airlie wrote:
> 
> Hey guys,
> 
> I've been writing dynamic power management code for the secondary
> GPUs, however a lot of these GPUs have audio codecs as a subfunction
> PCI device.
> 
> So we get 01:00.0 as the GPU and 01:00.1 as the HDMI audio device.
> 
> Now we have a single power switch for these devices, and generally the
> power switch is hit when the ACPI entry to D3 is called for the GPU
> and it shuts off the whole device.
> 
> So the problem I'm having is how to have the audio device
> (snd_hda_intel), understand that it needs to have the GPU devices D0
> called before it can do its own D0, and thats its D3 should be called
> before the GPU drivers D3.
> 
> Any pointers? Do I need to create a separate pm domain for these
> devices? how does the ordering work then?

Implementing pm_domain in both graphics and audio drivers, graphics as
a mater and audio a slave?


Takashi