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

[Wu Fengguang]

On Mon, Oct 26, 2009 at 06:31:45AM +0800, David Härdeman wrote:
> On Wed, Oct 21, 2009 at 09:38:12AM +0800, Wu Fengguang wrote:
> > On Wed, Oct 21, 2009 at 06:37:58AM +0800, David Härdeman wrote:
> > > On Tue, Oct 20, 2009 at 09:26:00AM +0800, Wu Fengguang wrote:
> > > >On Thu, Oct 15, 2009 at 01:40:53AM +0800, David Härdeman wrote:
> > > >> >Complete silence for how much time?
> > > >> 
> > > >> For the entire duration of the particular movie/audio track/video 
> > > >> clip/whatever.
> > > >> 
> > > >
> > > >I actually have a DG45FC box and have not run into this problem for
> > > >all the HDMI monitors I have. What's your monitor model?
> > > 
> > > A Samsung LE-55A956 LCD TV. But I think the problem is not with the 
> > > monitor (TV) but rather with the receiver that is between the DG45FC and 
> > > the TV. The receiver is a Marantz SR8002 with HDMI support.
> > 
> > Got it. If you have a HDMI capable TV or monitor, it would be possible to get
> > rid of the Marantz and check if the problem sticks :)
> 
> Nope, DG45FC <-> TV works fine (although only with stereo of course), so 
> the culprit is the Marantz which is either being picky or buggy. Judging 
> from from quick Google searches, HDMI related problems with audio/video 
> seems par for the course with lots of different manufacturers (oh joy).

Hmm..

> > OK. You can get more debug info if turning on
> > 
> > CONFIG_SND_VERBOSE_PROCFS=y
> > CONFIG_SND_VERBOSE_PRINTK=y
> > CONFIG_SND_DEBUG=y
> > CONFIG_SND_DEBUG_VERBOSE=y
> > CONFIG_SND_PCM_XRUN_DEBUG=y
> 
> Enabled in my latest tests, dmesg included below...

Thanks.

> > > >What if you change display
> > > >modes with xrandr?
> > > 
> > > Haven't tried that yet...currently running on 1920x1080 at 60 which should 
> > > (I guess) be one of the most common modes with modern LCD TV's.
> > 
> > The infoframe would be different for 2-channel pure music and 5.1 channel
> > movie. The video timing might also affect audio stream, because the HDMI
> > audio data is transfered in the gaps of video data.
> 
> I've tried a couple of different modes with xrandr, with both 2, 6 and 8 
> channels of audio but it doesn't seem to change anything.

OK.

> > > >HDMI codec/sink seem to take some time to response to the output
> > > >enable and new infoframe, so there are some delay. I've moved the HDMI
> > > >output enable command to module load time, this helps. The infoframe
> > > >is in theory created in run time based on the format of _each_ new
> > > >audio stream, so infoframe transmission has to be started/stopped
> > > >for each track..
> > > 
> > > So my current theory is along the line of HDMI audio infoframe or video 
> > > infoframe problems. Do you have any pointers where in the driver(s) 
> > > the infoframes (both audio and video) are generated so that I can add 
> > > some debugging statements to dump the frames and compare the working 
> > > and non-working scenarios?
> > 
> > I guess the infoframe itself should be identical for the same clip.
> > Have you tried upgrading to a recent Xorg/intel gfx driver?
> 
> Currently testing with kernel 2.6.32-rc5 (self-compiled) + intel-gfx 
> 2.9.0 and X11R7.4 (from Debian unstable).

That's fairly bleeding edge :)

> > Anyway, the kernel driver code is linux/sound/pci/hda/patch_intelhdmi.c
> > The relevant function is hdmi_setup_audio_infoframe(). Inside which the
> > hdmi_setup_channel_mapping() is not functioning for G45,
> > hdmi_setup_channel_allocation() is no-op for 2-channel music.
> > hdmi_debug_dip_size() and hdmi_clear_dip_buffers() can also be commented out.
> > And feel free to ask more questions :)
> 
> I think I found a bug in the infoframe generation, 
> hdmi_fill_audio_infoframe from sound/pci/hda/patch_intelhdmi.c has two 
> for loops which use sizeof(ai) but ai is a pointer to struct 
> hdmi_audio_infoframe so the size of a pointer is used rather than the 
> size of the struct meaning that the wrong number of bytes is written.

Good catch, thank you very much!

> After fixing that, the dmesg output when playing "speaker-test -c8 -twav 
> -D hdmi -l1" is:
> 
> [  866.169344] ALSA sound/pci/hda/hda_intel.c:1617: azx_pcm_prepare: 
> bufsize=0x10000, format=0x17
> [  866.169353] ALSA sound/pci/hda/hda_codec.c:1083: 
> hda_codec_setup_stream: NID=0x2, stream=0x5, channel=0, format=0x17
> [  866.176112] ALSA sound/pci/hda/patch_intelhdmi.c:446: HDMI: select CA 
> 0x13 for 8-channel allocation:  FL/FR LFE FC RL/RR RC FLC/FRC RLC/RRC 
> FLW/FRW FLH/FRH TC FCH
> [  866.176321] HDMI: ASP channel 0 => slot 0
> [  866.176354] HDMI: ASP channel 0 => slot 0
> [  866.176406] HDMI: ASP channel 0 => slot 0
> [  866.176438] HDMI: ASP channel 0 => slot 0
> [  866.176490] HDMI: ASP channel 0 => slot 0
> [  866.176533] HDMI: ASP channel 0 => slot 0
> [  866.176565] HDMI: ASP channel 0 => slot 0
> [  866.176617] HDMI: ASP channel 0 => slot 0
> [  866.176649] HDMI: ELD buf size is 64
> [  866.176691] HDMI: DIP GP[0] buf size is 13
> [  866.176733] HDMI: DIP GP[1] buf size is 10
> [  866.176775] HDMI: DIP GP[2] buf size is 30
> [  866.176817] HDMI: DIP GP[3] buf size is 30
> [  866.176859] HDMI: DIP GP[4] buf size is 0
> [  866.176901] HDMI: DIP GP[5] buf size is 0
> [  866.176943] HDMI: DIP GP[6] buf size is 0
> [  866.176986] HDMI: DIP GP[7] buf size is 0
> [  866.179041] ALSA sound/pci/hda/patch_intelhdmi.c:342: HDMI: DIP GP[0] 
> buf reported size=13, written=32
> [  866.181209] ALSA sound/pci/hda/patch_intelhdmi.c:342: HDMI: DIP GP[1] 
> buf reported size=10, written=32
> [  866.183271] ALSA sound/pci/hda/patch_intelhdmi.c:342: HDMI: DIP GP[2] 
> buf reported size=30, written=32
> [  866.185385] ALSA sound/pci/hda/patch_intelhdmi.c:342: HDMI: DIP GP[3] 
> buf reported size=30, written=32
> [  866.185574] XXX: Writing audio inf: 0x84 0x01 0x0A 0x57 0x07 0x00 
> 0x00 0x13 0x00 0x00 0x00 0x00 0x00 0x00
> [  872.032225] ALSA sound/pci/hda/hda_codec.c:1096: 
> hda_codec_cleanup_stream: NID=0x2
> 
> (The XXX line was added by me to print the audio infoframe)

FYI, I'll write another Intel GPU tool to dump the audio infoframe
(among others) directly from the GPU registers :)

> I think (if I understood the code correctly), that "DIP GP[0]" holds the 
> infoframe, but I don't understand why it would report a buf size of 
> 13...the audio infoframe is 14 bytes (3 header + 1 checksum + 10 body)?

Good question. I guess I made it wrong again. The checksum field may
be auto-generated by hardware:

        The HDMI specification defines a data island packet with a
        header of 4 bytes (3 bytes content + 1 byte ECC) and packet
        body of 32 bytes (28 bytes content and 4 bytes ECC). Note that
        the ECC bytes are not present in the DIP content populated by
        software and are hardware generated.
                                                      - from HDA-034-A2.pdf

> Also, what does the GP[1..3] buffers hold?

They are for ACP and ISRC1/2 (not utilized by driver for now):

        When audio data is transmitted over the HDMI link, associated
        control information is transmitted as "Data Island Packets"
        over the link. Some of the packet types applicable to audio
        are ACP packets (for content protection), ISRC1/2 (for content
        info), Audio infoframe etc. For a detailed list of control
        packets and respective formats, please refer to the HDMI
        specification. 

> Anyway, even with the above for loops fixed, I still have the same 
> problems (not that weird perhaps since all the bytes that were being 
> missed anyway defaulted to 0x00).

Yeah. I have always be wondering whether the checksum field is
necessary. Removing it seems to change nothing. Anyway the number 13
is a strong indication for removing it.

> I've noticed that if a run this:
> 
> 	while true; do
> 		speaker-test -t wav -c 8 -D hdmi -l 1
> 		speaker-test -t wav -c 2 -D hdmi -l 1
> 	done
> 
> it always works, but this:
> 
> 	while true; do
> 		speaker-test -t wav -c 2 -D hdmi -l 1
> 	done
> 
> doesn't.

This is weird for now. Thanks for the tip!

> Not sure what to make of it, the intel hdmi driver doesn't seem to do 
> anything special if the parameters (like channel count) change between 
> clips.

Thanks,
Fengguang