[Intel-gfx] [Alsa-user] intel-hda: sound via HDMI only when using interlaced modes

[Takashi Iwai]

At Sun, 10 Feb 2013 02:16:14 +0100,
David Härdeman wrote:
> 
> On Thu, Feb 07, 2013 at 11:00:13AM +0100, Daniel Vetter wrote:
> >On Wed, Feb 06, 2013 at 10:35:33PM +0100, David Härdeman wrote:
> >> I'll break etiquette here and include the entire original message below
> >> (and top-post!) since I'm sending this to intel-gfx as well.
> >> 
> >> Since the previous mail I've tested a more recent kernel (3.8-rc6),
> >> swapping HDMI cables and a firmware update on the receiver, none of it
> >> helped.
> >> 
> >> I've also noticed that:
> >> 
> >> a) switching between 1080p30 and 1080p50 or 1080p60 is enough to make
> >> the sound go away (higher frame rates) or work (1080p30). So, it has
> >> nothing to do with interlacing.
> >> 
> >> The only difference between the output of all the intel*dump tools when
> >> running 1080p30 and 1080p60 is included below. It's interesting to note
> >> that all the modes that don't work have fdi_lanes = 2 while the working
> >> ones have fdi_lanes = 1 (port width in intel_reg_dumper-speak).
> >> 
> >> I'm CC:ing the intel-gfx list as well as the ALSA list since I'm not su
> >> sure where the problem lies anymore...suggestions?
> >
> >I'm far away from an hdmi/snd expert, but iirc the bandwidth to squeeze
> >hdmi sound packets between the video frames is limited. And atm our code
> >does not bother with checking for that at all (and updating the
> >capabilities of the hdmi snd widget). But that's just an idea, I have no
> >idea how much bandwidth there actually is.
> 
> I should add that I've now installed Win7 on a separate HD. Windows has
> no problems at all with audio over HDMI, no matter which resolution
> and/or refresh rate, so I think cabling and other HW issues can be ruled
> out. The problem is Linux-specific.
> 
> And, as I mentioned before, the TV *is* willing to accept and decode the
> audio signal, so it appears that the audio stream is there....but it's
> probably incompatible in some minor way...and the receiver is being
> picky. That's my guess.
> 
> Anyway, how should I proceed? File a bug? In the kernel bugzilla or ALSA
> bugtracker or somewhere else?

FYI, ALSA bug tracker is down (and I hope it's no longer used), so put
it in either freedesktop or kernel bugzilla.


Takashi