[LAD] jackd and usb hub

Robin Gareus robin at gareus.org
Wed Oct 13 22:00:48 UTC 2010

On 10/13/10 20:01, Luis Garrido wrote:
> On Wed, Oct 13, 2010 at 2:02 PM, Robin Gareus <robin at gareus.org> wrote:
>> With the USB2 hub I also get
>> ALSA urb.c:856: cannot submit datapipe for urb 0, error -28: not enough
>> bandwidth
>> ALSA midi.c:214: urb status -32
>> messages and jackd won't start.
> Does the hub cause this problem also through a regular USB port (not PCMCIA)?

yes it does.

>> but connecting the UA-25 directly to the PCMCIA/USB2 card works if I
>> also connect some external power supply to the PCMCIA card. Did you try
>> that?
> Believe it or not, that combination hadn't crossed my mind yet: using
> the brand new shiny and otherwise useless hub as a 16 € glorified 5V
> regulator between its power supply and the PCMCIA card. Why the heck
> not, eh? One fewer layer, too.
> Well, there's my workaround, thanks Mr. Gareus! But (it couldn't have
> been that easy, could it?) only works on one of the two USB/PCMCIA
> ports. 

Weird. Well, just use the one that works :-p

> Trying to use the other one gets me this nice message:
> ALSA sound/usb/usbaudio.c:1348: 40:1:1: usb_set_interface failed
> Bleh.
> Anyone interested in a moderately used Edirol UA-25 interface with
> some occasional -74 dB noise at 13.1 kHz, and a penchant for serial
> (bus) killing?

what are you going to do? get a Firewire device?

> Anyway, I think this hub issue is worth looking into. Old USB 1.1 hubs
> don't mess with realtime audio and new USB 2.0 do? 

It looks like (in my case) the hub is actually translating from USB2 to
USB1.1 and thereby causes some overhead.

If I connect both an external HDD and a cheap (usb1.1) mouse to the hub
(which is connected to the USB port of my laptop) the HDD still gets max
throughput (>30MB/s).

> Now that's not
> exactly what I'd call an improvement. What can we expect from USB 3.0?
> Cheers,
> L

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