How to hook HDMI audio to vga-switcher?

Dave Airlie airlied at
Wed Apr 25 01:42:02 PDT 2012

On Wed, Apr 25, 2012 at 9:36 AM, Takashi Iwai <tiwai at> wrote:
> 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:
> 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.

I'd envisage some sort of notifier interface that other non-gpu
drivers can hook into
to be told about the current state of the GPU device. So some sort of separate
client type with a callback when we turn on/off the device so other drivers can
init themselves.


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