jackocleebrown;696408 Wrote: 
> Using kernel 1 and 2 I get:
> 
> asyc-dac hack: changing datainterval from 0 to 1
> 2:1:1: cannot get freq at ep 0x1
> iso: int: 2 usec: 12 c_usec: 0 maxp: 585 raw_mask: 0000000f tt_usecs:
> 464
> enable_periodic
> iso: int: 128 usec: 1 c_usec: 1 maxp: 3 raw_mask: 00001c01 tt_usecs:
> 12
> fsl-ehci fsl-ehci.0: request c732f760 would overflow (2048+128>2048)
> cannot submit syncpipe for urb 2, error -27: internal error
> disable_periodic
> 
> Same error just with some other info in there.

I believe I know what is going on.  I suspect it is because your dac
asks for frequency reports every 128 ms, whereas other dacs ask for
them more frequently.  There is a known limitation in the kernel usb
scheduler code where infrequent requests get refused.  I have two
routes to fix this: 1) adding more patches to the usb scheduler code
from more recent linux kernels, 2) ignoring the request from the dac
and always using a more frequent interval to poll for frequency.  I
will look at next weekend and try to do 1) as it seems more general -
please look out for an update.


-- 
Triode
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