On Sun, 25 Jul 2010, Sam Gentle wrote: > Hi there, > > I have a new-ish device made by Hercules called the Deejay Trim, it's > a USB audio interface with an inbuilt USB hub. 3 ports of the hub are > made available as external ports, and the fourth is used internally to > connect the audio device. Looks like this: > http://www.hercules.com/uk/DJ-Music/bdd/p/102/deejay-trim-4-6/ > > When I attempt to record from it, I get "ALSA start: broken pipe" and > this error in my dmesg: "cannot submit datapipe for urb 0, error -28: > not enough bandwidth" > > Having done a bit of research, I've seen some indication that some > kernel config options might fix it, namely USB_EHCI_TT_NEWSCHED > (already enabled on my kernel) or USB_EHCI_SPLIT_ISO (which seems to > have been removed - does that mean it's not needed?) It means that symbol doesn't exist any more. > It seems one possible reason for such an error is not having per-port > transaction translators. I've looked at the lsusb dump for the hub, > and I see something really peculiar. > > Bus 001 Device 014: ID 05e3:0607 Genesys Logic, Inc. > [...] > bDeviceProtocol 2 TT per port > [...] > bNumInterfaces 1 > [...] > bInterfaceProtocol 1 Single TT > iInterface 0 > [...] > bInterfaceProtocol 2 TT per port > iInterface 0 > > bNumInterfaces is 1, but there are two interface descriptors with > different bInterfaceProtocol values - is that expected? Yes, it is. If you look at the parts of the listing you trimmed out, you'll see that the two entries above are for the _same_ interface, in different alternate settings. That's how hubs with per-port TTs work. In any case this doesn't make any difference, because you're only using one of the ports. > I also notice that 05e3:0607 isn't in http://www.linux-usb.org/usb.ids > - I'm not sure if that's important. It isn't. > Anyhow, I've included my kernel > config (stock Ubuntu 2.6.32-24) and lsusb -v output. Anyone have any > ideas? I'm happy to provide any more information if it'll help. You might try disconnecting the webcam. (Or if it's hard-wired into the machine and you can't disconnect it, unload its driver.) Can you provide a usbmon trace? Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
