[vox-tech] DMA conflict

Nick Schmalenberger nschmalenberger at fastmail.fm
Sat Oct 30 11:51:12 PDT 2004


list,
First, I solved the problem I posted about a few weeks ago wtional
aeronautical beacons is
being phased out and the frequencies also arhere I was having trouble
configuring the sound on my laptop. For some reason, installing udev
fixed it. Now I'm having a different problem in a different computer. In
this other computer, I have an ISA soundcard. When it works, it uses
two DMA numbers, 1 and 5. /proc/dma says:
 1: SoundBlaster - 8bit
 4: cascade
 5: SoundBlaster - 16bit
. I guess cascade is shared by the PCI devices. For PCI devices, I have
a video card, a NIC, a SCSI controller, the south bridge, and a TV tuner
card. The TV card has been causing the most trouble, but there are other
problems too. If I use an AGP video card instead of the PCI one, the
computer hangs at boot just after the sound card has been initialized.
When I have the TV card in, the sound card driver doesn't get loaded. I
can modprobe it manually, but it still doesn't work. When I watch TV, it
is very unstable and if I try to move the window around or use a control
button there will be some video problem like where the window or button
was will turn orange or the computer will hang. The bttv driver FAQ
indicates that there may be DMA problems:
http://linux.bytesex.org/v4l2/faq.html#oops
It says to disable DMA for IDE. Is there some better way? The DMA
channels are supposed to be shared, right? If I have to disable DMA for
IDE how do I do it? In Documentation/ide.txt of the kernel sources, I
can see where it says to argue to the kernel for a particular drive to
use DMA, but I can't see how to disable DMA. Anyway, DMA exists for a
reason I guess, so I'd prefer to make it work if possible. This message
indicates that my chipset, VIA MVP3, may have DMA problems:
http://www.ussg.iu.edu/hypermail/linux/kernel/0308.1/0375.html . So do I
 just have a chipset that doesn't work well with DMA or what?

Also, the tuner on my card that is autodetected is the wrong one because
the channels are offset, so I need to manually argue for a different
tuner. There is nothing in /etc/modprobe.d/ about bttv, or my NIC or
SCSI controller for that matter. I suppose the NIC module is called when
bringing up network interfaces, and the SCSI controller module is called
when bringing up drives, but when is bttv called? How do I give
arguments to it? Thanks in advance.
Nick


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