[alsa-devel] Tascam US-428 USB Problems

Karsten Wiese fzu at wemgehoertderstaat.de
Thu Aug 23 12:05:41 CEST 2007

> >
> > USB 1.1 transfers happen at 1ms bounderies. Setting 64Frames/period period
> > interrupts will happen within 1ms or 2ms distances.
> I was not aware of the 1ms granularity for USB interrupts.  Would USB
> 2.0 or Firewire offer a better granularity?

Technically both operate at down to 1/8ms.

Linux's USB 2.0 ehci driver doesn't go there and limits isochronous
transfer granularity at 1ms.
I posted a patch to linux-usb-devel, which enables 1/8ms granularity
isochronous transfer.
There was exactly 0 answer to it.
And I was too lazy to follow up on that ;-)

Regarding Firewire: I guess the "new stack" can operate at
1/8ms granularity.


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