From mboxrd@z Thu Jan  1 00:00:00 1970
From: Wu Fengguang <fengguang.wu@intel.com>
Subject: Re: [PATCH v5] drm/i915: pass ELD to HDMI/DP audio
 driver
Date: Thu, 10 Nov 2011 21:53:43 +0800
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To: Takashi Iwai <tiwai@suse.de>
Cc: "Wang, Zhenyu Z" <zhenyu.z.wang@intel.com>, "intel-gfx@lists.freedesktop.org" <intel-gfx@lists.freedesktop.org>, "Barnes, Jesse" <jesse.barnes@intel.com>, Jeremy Bush <contractfrombelow@gmail.com>, Christopher White <c.white@pulseforce.com>, "Bossart,
	Pierre-louis" <pierre-louis.bossart@intel.com>
List-Id: intel-gfx@lists.freedesktop.org

On Thu, Nov 10, 2011 at 09:51:50PM +0800, Wu Fengguang wrote:
> > > > > 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

[the stage of ELD_Valid temporarily goes 0 while monitor is still there]

> take NO action like stopping the audio stream -- just let go of it for
> the moment.
> 
> Thanks,
> Fengguang