USB audio device on Raspberry Pi - link_elf: symbol isa_dmastatus undefined

[Ian Lepore]

On Wed, 2014-04-30 at 11:21 +0200, Hans Petter Selasky wrote:
> On 04/30/14 11:14, Scott Aitken wrote:
> > Hi again,
> >
> > good call on the kernel recompile.  I added sound and uaudio to the kernel
> > and low and behold things improved:
> >
> >
> > root at raspberry-pi:/mnt # dmesg
> > ...
> > ugen0.4: <danyigao audio equipment> at usbus0
> > uaudio0: <danyigao audio equipment DARED AUDIO, class 0/0, rev 2.00/1.00, addr 4> on usbus0
> > uaudio0: Play: 96000 Hz, 2 ch, 24-bit S-LE PCM format, 2x8ms buffer.
> > uaudio0: Play: 48000 Hz, 2 ch, 24-bit S-LE PCM format, 2x8ms buffer.
> > uaudio0: Play: 44100 Hz, 2 ch, 24-bit S-LE PCM format, 2x8ms buffer.
> > uaudio0: No recording.
> > uaudio0: No MIDI sequencer.
> > pcm0: <USB audio> on uaudio0
> >
> > However, when I play a file to /dev/dsp, I get an error in dmesg:
> >
> > root at raspberry-pi:/mnt # cat /bin/ls > /dev/dsp
> > cat: stdout: Invalid argument
> > root at raspberry-pi:/mnt # dmesg
> > ...
> > pcm0: chn_write(): pcm0:virtual:dsp0.vp0: play interrupt timeout, channel dead
> >
> 
> Hi,
> 
> In the "sys/dev/usb/controller/dwc_otg.c" driver the isochronous method 
> which your audio device is using, is not implemented, because it causes 
> excessive interrupts. So the USB transfer simply times out.
> 
> --HPS

You mentioned 8k interrupt/sec, while that may be too many in some "it
could be better" sense, it shouldn't be enough to cause problems.  I was
doing some testing on a wandboard (about twice as fast an an rpi) with
more than 20k int/sec without having any problems.

-- Ian