[alsa-devel] Status of CMI9738 and SiS7012

[Takashi Iwai]

Hi,

Please don't drop Cc to alsa-devel...

At Wed, 28 Mar 2007 10:23:22 -0600,
Rob Franklin wrote:
> 
> On 3/28/07, Takashi Iwai <tiwai at suse.de> wrote:
> > At Tue, 27 Mar 2007 10:44:23 -0600,
> > Rob Franklin wrote:
> > >
> > > On 3/27/07, Takashi Iwai <tiwai at suse.de> wrote:
> > > > At Tue, 27 Mar 2007 08:49:05 -0600,
> > > > Rob Franklin wrote:
> > > > >
> > > > > Hi All,
> > > > >
> > > > > I posted a question a couple of weeks ago to the alsa-users list
> > > > > (Can't get spdif working with ALSA and FC6 on ECS L4S5MG/651+
> > > > > motherboard), but never got a response.
> > > > >
> > > > > I have been looking at the ALSA source code for the AC'97 codec on my
> > > > > board  (CMI9738) and the source code for the intel8x0 driver (for my
> > > > > SiS 7012).  However, as far as I can tell from looking at the source,
> > > > > S/PDIF is not enabled/supported for this combination of devices.
> > > > > Additionally, Googling around I haven't found any mention of people
> > > > > getting spdif working with ALSA and a CM9738 / SiS7012 combo.
> > > > >
> > > > > I am wondering whether anyone on the developer list can confirm that
> > > > > this is the case.  Also, if this is the case can someone give me an
> > > > > idea of what would be required to get this working.  The system is
> > > > > setup with dual boot and so I could grab some of the values from
> > > > > windows using a PCI sniffer, and I might be able to do some hacking on
> > > > > the source code and submit a patch if someone could help guide me in
> > > > > the right direction.
> > > >
> > > > Are you sure it's CM9738?  AFAIK, CM9738 doesn't support SPDIF at
> > > > all, but CM9739 does...
> > > >
> > > That was my first thought too, but I pulled open the case last night
> > > and verified that it was indeed a 9738.  The download page from the
> > > motherboard manufacturer has a driver for CMI9738 and a CMI9738/9739
> > > driver (http://www.ecsusa.com/downloads/drivers_sound.html).  I am
> > > wondering if there are two different versions of this chip.
> > >
> > > Here is the output from lspci -vv for the sound device:
> > >
> > > 00:02.7 Multimedia audio controller: Silicon Integrated Systems [SiS]
> > > AC'97 Sound Controller (rev a0)
> > >         Subsystem: Elitegroup Computer Systems Unknown device 0a44
> > >         Control: I/O+ Mem- BusMaster+ SpecCycle- MemWINV- VGASnoop-
> > > ParErr- Stepping- SERR- FastB2B-
> > >         Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium
> > > >TAbort- <TAbort- <MAbort- >SERR- <PERR-
> > >         Latency: 32 (13000ns min, 2750ns max)
> > >         Interrupt: pin C routed to IRQ 22
> > >         Region 0: I/O ports at d000 [size=256]
> > >         Region 1: I/O ports at d400 [size=128]
> > >         Capabilities: <access denied>
> > >
> > > One thought that I had was to force the AC'97 driver to detect the
> > > chip as a 9739 instead of a 9738 to see whether my 9738 can work as a
> > > 9739.  But I'm not sure how to do that short of modifying the source
> > > code and recompiling the kernel module.
> >
> > First check whether its codec id is CMI9738, see
> > /proc/asound/card0/codec97#0/* files.  If it's really CM9738, you can
> > hack pci/ac97/ac97_codec.c to replace patch_cm9738 with patch_cm9739
> > in snd_ac97_codec_ids[].
> >
> Here are the first couple of lines from /proc/asound/card0/codec97#0/ac97#0-0 :
> 
> 0-0/0: C-Media Electronics CMI9738
> 
> PCI Subsys Vendor: 0x1019
> PCI Subsys Device: 0x0a44
> 
> Last night I hacked the ac97_codec.c and recompiled snd-ac97-codec.ko,
> and now the file reads
> 
> 0-0/0: C-Media Electronics -- rob CMI9739
> 
> Everything seems to be working the same as it was before, and I can
> get stereo sound from the line-out jack just fine.  However, when I
> try to play back sound using the spdif I get the following:
> 
> $ aplay -D plug:iec958 ac3_48khz_diatonis_soal.ac3
> ALSA lib setup.c:555:(add_elem) Cannot obtain info for CTL elem
> (MIXER,'IEC958 Playback Default',0,0,0): No such file or directory

I guess the control element wasn't created indeed because of lack of
SPDIF feature on the codec.

patch_cm9739() checks the availability of SPDIF bit (SPCV) and turn
off the whole SPDIF feature if the bit isn't set.  You can avoid that
check just for testing.

If this doesn't work, the possible situation is that the SPDIF is
transmitted directly from the controller chip without AC97 codec.
Unfortunately, we have no hardware information about SIS7012, so don't
know whether it's even possible, and how to control it.

> Is there a script I need to run or file I need to update my list of
> CTLs (I have seen references to alsaconf and snddev on the web but
> neither seems to be included with my FC5 install of alsa-utils)?

% alsactl -f somefile store

> Also, is there any easy way to reload the snd-ac97-codec.ko module.  I
> tried removing the modules with "rmmod snd-ac97-codec" and "modprobe
> snd-ac97-codec".  The module came out ok, but I got a  bunch of errors
> like this when I tried to reinsert the modules:
> 
> Mar 27 21:16:46 XXXX kernel: snd_ac97_codec: Unknown symbol snd_info_register
> Mar 27 21:16:46 XXXX kernel: snd_ac97_codec: disagrees about version
> of symbol snd_ctl_add
> 
> So right now I am rebooting the machine every time I want to replace
> snd-ac97-codec.

Seems that you still have the old modules on memory while installing
the new modules.  First unload all snd related modules, then reload
again.

Otherwise, something wrong with the build with your kernel tree.
I never used FC or RedHat, so can't answer about it.


Takashi