[mythtv-users] Trouble setting up two sound cards in same box

maarten mythtv at ultratux.org
Wed Mar 17 13:07:29 EST 2004

On Wednesday 17 March 2004 18:01, Chuck Connors wrote:
> *Flame retardent disclamier*
> I realize that this is not the alsa mailing list, nor is it the knoppmyth
> forums.  I have posted my problem to both the alsa mailing list and the
> knoppmyth forums and receive a bit of help, but my sound problems presist.
> I am petitioning this list for help as I am under the assumption that
> others may be running two bttv cards with multiple sound cards in the same
> box *End disclaimer*
> Here's the situation.  I am currently running KnoppMyth (a Knoppix based
> distro of Mythtv).  I have the system running fine with one bttv card (an
> ATI TV Wonder VE) and the onboard sound (Sis chipset).  I decided I wanted
> another tv tuner so I bought another bttv card (AITech Wave).  Because both
> of my bttv cards do not have btaudio, I am forced to have a sound card
> dedicated for each card.  I decided to add a Cmedia pci card, and have been
> having troubles ever since.  Thus this message.  At the moment, the onboard
> sound works fine, but I'm not getting anything from the pci card I added.
> Here is what I get when I do an 'lspci -v' in regards to the sound cards:
> 00:02.7 Multimedia audio controller: Silicon Integrated Systems [SiS] Sound
> Controller (rev a0)
>         Subsystem: C-Media Electronics Inc: Unknown device 0300
>         Flags: bus master, medium devsel, latency 64, IRQ 10
>         I/O ports at dc00 [size=256]
>         I/O ports at d800 [size=64]
>         Capabilities: [48] Power Management version 2
> 00:0f.0 Multimedia audio controller: C-Media Electronics Inc CM8738 (rev
> 10) Subsystem: C-Media Electronics Inc CMI8738/C3DX PCI Audio Device Flags:
> bus master, medium devsel, latency 64, IRQ 12
>         I/O ports at b800 [size=256]
>         Capabilities: [c0] Power Management version 2

IRQ 12 is _always_ used for the PS/2 mouseport IIRC. Plus you mention below 
that it is also used by USB. Thus, I'd say play around with the BIOS IRQ 
settings to see if you can get it on a different IRQ.  Please disable any 
onboard stuff you do not use (if you didn't already...). This specifically 
includes (when applicable) floppy controller, parallel port, serial ports, 
midi port, etc. etc.
If this doesn't fix it and you are unable to get the card on it's own IRQ, 
change the order of the cards in the PCI slots as they are hardwired to IRQ 
lines; all AGP + PCI slots share (at most) 4 IRQ lines so finding out which 
slot(s) uses which lines may be helpful to you.
Please note that linux support IRQ sharing just fine, BUT only if the 
driver(s) in question play nice. So when in doubt, try and make sure the 
troublesome card(s) use a single IRQ.

> I just noticed that my USB controller and the C-media pci card are both
> using
> IRQ 12 .  Can this be the cause of the problem, or do they both 'share' IRQ
> 12?

Um, they do indeed share an IRQ but that's not the point. Do they play NICE 
while sharing the IRQ ? is the REAL question.  If one of those has the notion 
of "sharing" that Eric Cartman has, then the other card is starved for 
resources and will not work.  ;-)

Dunno if all this helps any, but just a few random thoughts...  
Good luck.


Yes of course I'm sure it's the red cable. I guarante[^%!/+)F#0c|'NO CARRIER

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