I have an XXS1500 (from myCable.de) based on the
Au1500 MIPS. I am trying to make a SoundBlaster Live!
External USB card working.
Regardless of whether I use the OSS or ALSA drivers, I
get the same corrupted output: A high-frequency and
noise alternating in frequency. Always the same
pattern when I play the same song.
Even when playing from /dev/zero, I get noise.
I happened to read the reply by Dale Farnsworth to the
subject "Problems with usb-ohci.c driver on PPC405 and
ISOCHRONOUS transfers":
> The problem is that while td->hwPSW is an array of
> u16, the OHCI spec (incorrectly, IMHO) describes it
> as an array of u32, with each element containing 2
> u16 fields in little endian order. IBM (as well as
> Motorola/Freescale in the MPC5200) implemented
> according to the spec and the result is an array of
> big-endian u16 elements which the OHCI hardware uses
> in this order: hwPSW[1], hwPSW[0], hwPSW[3],
> hwPSW[2], etc.
I wonder if a similar problem could exist for the
XXS1500 (although I haven't analysed whether the
soundcard really uses isochronous transfers)?
In order to enable the SPDIF output, I have written a
program that writes a number of USB control messages
to the soundcard (equal to those sent by the windows
driver when the card is plugged in). This apparently
works fine - I get light in one of the LEDs on the
box. So the control messages seem to work.
The device uses kernel 2.4.21 with a patch applied to
the usb-ohci.c because the builtin OCHI does not sit
on a PCI bus.
In dmesg I also get the following messages, but I am
not sure if they are related to the problem:
usb.c: usb-check-bandwidth FAILED: was 697, would be
1378, bustime = 681 us
I would be happy to hear any suggestions.
-tim
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