How to hook HDMI audio to vga-switcher?

[Takashi Iwai]

Hi Dave,

in kernel bug 43155, we found out that the HDMI audio controller on
AMD graphics is also disabled when the graphics chip is disabled via
vga-switcher:
    https://bugzilla.kernel.org/show_bug.cgi?id=43155

This screws up the sound driver, takes too long time for boot.

Since the audio controller/codec becomes active again once when the
graphics is turned on, the best solution would be to add a client to
vga-swicheroo for handling the status of the HDMI audio controller.

But, looking at the current vga_switcheroo.c, it seems that the
current code assumes only two clients and doesn't consider about
non-graphics PCI entries.

As a workaround, I'm thiking of a sort of slave client belonging to
the video client, so that a callback like set_gpu_state() can be
called.

Or, if you have any better idea, let me know.


thanks,

Takashi