[alsa-devel] HDMI codec, way forward?

[Vinod Koul]

On Wed, Oct 21, 2015 at 12:11:08PM +0300, Jani Nikula wrote:
> On Tue, 20 Oct 2015, Vinod Koul <vinod.koul at intel.com> wrote:
> > On Tue, Oct 20, 2015 at 09:08:00AM +0100, Russell King - ARM Linux wrote:
> >> > > Currently i915/audio component works as you described.  The audio is
> >> > > optional and HDMI graphics works without audio, while HDMI HD-audio
> >> > > mandates i915 graphics.
> >> > 
> >> > Right, but we also add additional interface on top of this to allow
> >> > things like ensuring display is on when audio wants to run and now
> >> > notification for events.
> >> > 
> >> > I don't see a reason why this can be used as single interface to bind as
> >> > well as talk to display from various components, unless I missed obvious
> >> > which prevent us from doing this in non i915 cases...
> >> 
> >> Maybe I can comment more specifically if I saw the code.  Right now all
> >> I'm aware of is this idea without any code, and I don't like it.
> >
> > Ok, i will be post my patches tomorrow. FWIW uses interface in
> > sound/hda/hdac_i915.c for display power up/down
> 
> Side note, some of the Intel HD audio controller registers are in a
> power domain controlled by i915. The audio drivers needs to do power
> get/put, otherwise the audio driver loses its marbles when i915 switches
> off power. OTOH audio needs to be a good citizen so i915 can reach low
> power states.
> 
> Just a shout from the back, unsure if this is relevant at this point...

We are putting the get/put calls in driver's suspend and resume handler,
that way we would suspend when not in use and ensure display suspends
too...

-- 
~Vinod