[Intel-gfx] [PATCH v5] drm/i915: pass ELD to HDMI/DP audio driver

[Wu Fengguang]

> > > > So maybe the hardware is in some state that is unable to provide the
> > > > real ELD content?
> > > That's my guess as well. I think the hardware may still be doing some 
> > > form of data negotiation with the HDMI display device at that stage, and 
> > > doesn't have the copy of the EDID+ELD buffer until a tiny bit later. 
> > > Possibly?
> > 
> > Look at the below dmesg. The ELD seem to available immediately after the DPMS
> > state setting..
> 
> Interesting.  Does HDMI audio work at all while HDMI DPMS off?
> It clears SDVO_ENABLE bit, so this might turn off both video and
> audio?

We normally see transient blank screen and silence of audio when
switching the video mode.

The spec says that at this short stage the HDMI/DP audio driver should
take NO action like stopping the audio stream -- just let go of it for
the moment.

Thanks,
Fengguang