HDMI audio on R500

[Russ Dill]

On Mon, Mar 23, 2009 at 4:20 PM, Alex Deucher <alexdeucher at gmail.com> wrote:
>
> On 3/23/09, Russ Dill <russ.dill at gmail.com> wrote:
> > On Mon, Mar 23, 2009 at 3:29 PM, Alex Deucher <alexdeucher at gmail.com> wrote:
> >  > On 3/23/09, Russ Dill <russ.dill at gmail.com> wrote:
> >  >> I have a laptop with an HDMI output. In Vista, I can get the Realtek
> >  >>  HD audio driver to pass audio through the HDMI interface. In Linux, no
> >  >>  amount of fiddling with IEC958 switiches and PCM devices will get
> >  >>  audio to come through the HDMI interface.
> >  >>
> >  >>  00:00.0 Host bridge: ATI Technologies Inc RS480 Host Bridge (rev 10)
> >  >>  [...]
> >  >>  00:14.2 Audio device: ATI Technologies Inc IXP SB4x0 High Definition
> >  >>  Audio Controller (rev 01)
> >  >>  [...]
> >  >>  01:00.0 VGA compatible controller: ATI Technologies Inc M56P [Radeon
> >  >>  Mobility X1600]
> >  >>
> >  >>  An alsa developer was thinking that since the video chip interfaces
> >  >>  with the TMDS encoder chip and must somehow be involved. Is anyone
> >  >>  aware of any registers or bits that would enable HDMI audio
> >  >>  pass-through?
> >  >
> >  > Native HDMI audio support is only available on RS6xx/R6xx/R7xx chips.
> >  > I suspect there is either some platform specific magic required in to
> >  > get it to work (i.e., some external component does the audio/video
> >  > mixing), or your laptop's oem used an external hdmi encoder.  Can you
> >  > send me your video bios?
> >  >
> >  > as root:
> >  > cd /sys/bus/pci/devices/<pci bus id>
> >  > echo 1 > rom
> >  > cat rom > /tmp/vbios.rom
> >  > echo 0 > rom
> >
> >
> > Attached
> >
> >
>
> Looks pretty standard; internal tmds used for hdmi port.  I suspect
> hdmi audio is implemented via some oem-specific solution.

I had a chance to find the chip that powers this. Its a Silicon Image
TMDS ParallelLink Sil 1930.

http://www.siliconimage.com/docs/1390_1930_1368_FINAL.pdf

The product brief says that it connects with I2S, S/PDIF, or HD-Audio
to the audio codec and I2C to the GPU. I'm not sure if the GPU
controls the audio pass-through via I2C or not.

I don't think any datasheets are publicly available.