[Intel-gfx] Problems with HDMI audio on Intel DG45FC motherboard

[David Härdeman]

I've done some more testing...

I managed to borrow a DG45FC based computer with Windows 7 (32-bit, using
HDMI driver 14.6 from Intel's website) from a colleague over the weekend.

Under Windows 7, HDMI audio with my receiver just works when using the
Windows drivers (no complete-track-silence, no initial 0.5s silence). If I
use the control panel application to configure a 5.1 speaker setup, the
corresponding 5.1 speaker indication lights up on the receiver LCD and
stays on whether I'm playing stereo sounds (like Windows event sounds) or
multi-channel sources (tested with a DVD played using VLC with software
decoding of the AC3 track to 6 channel PCM stream). This suggests that my
issues *can* be resolved by hacking the driver :)

The windows driver also has some interesting registry entries referring to
"SilentStream" and "VCFG", the latter probably referring to the VCFG bit
in the digital converter control reg in section 7.3.3.9 of the HDA spec).

Also, it's interesting to note that when I am playing a working audio
sample under Linux, then pause and resume playing (using the UI controls),
there are no hiccups and no initial silence when the player resumes (from
a quick reading of the code, the audio infoframe should still be
transmitted, only DMA of audio data is stopped when pcm is paused).

Perhaps I've been going down the wrong path by focusing too much on the
audio infoframe side of things.

I wonder if the approach taken by the Windows drivers when there is
nothing to play is more similar to the pause/play commands in the Linux
driver and if it would be a big undertaking to make the Linux driver do
something similar...?

(Another option I'm planning to look into is whether power-saving might
interfere with normal HDMI audio operation.)

On Mon, November 2, 2009 09:57, Wu Fengguang wrote:
> FYI, I worked up a patchset which incorporates your patch
> and plan to submit it some time later.  Tests OK on my side :)

Which kernel version is the patchset based on? I couldn't apply it to
2.6.32-rc5 or git head (which is what I've been using for your previous
patchsets).

-- 
David Härdeman