3 Feb
2011
3 Feb
'11
12:40 a.m.
Which kernel?
Ubuntu Linux 2.6.35-25-generic
http://packages.ubuntu.com/maverick-updates/linux-image-2.6.35-25-generic
I've tried various kernels from 2.6.32 to 2.6.35 various Ubuntu and Debian
kernels. All experience the same. I have not yet compiled a kernel myself
since it's a lot of work and the performance gains are negligible. Since the
problem persists in all kernels I've tried it makes me suspect that the bug
is in the master tree not something that was added on in a distro kernel.
Shooting from the hip (and also digging in 2.6.26.5
sources)... looks
like there was a timeout when calling usb_set_interface()
(drivers/usb/core/message.c). The urb transfers look like they
stalled rather than failed to allocate bandwidth. That makes me think
there's a bad cable, bad USB controller, bad USB controller /driver/,
bad format request, bad device, or something like that.
That sounds consistent with my reports. It's speculation, but at least we
have that...
I bought two PCI USB cards to test against. One is PCI Express USB 3.0 the
other is PCI USB 2.0 - I'll report the results.
Assuming that the on-board hardware is being unusually slow - this ought to
fix it. If it's deeper in the core hardware I should probably scrap this
board and get something that works properly. Either way I ought to know
something soon. :-D
I'll add the USB cards tonight. Stay tuned! :-D
...Rods ;-)