On Mon, 18 Feb 2008, Michael SCHINDLER wrote:
> > > Judging from your log, the reason the handover occurs is because your
> > > device doesn't support high-speed operation. To confirm this, let's
> > > see what "lsusb -v" has to say about the device.
>
> The output from lsusb -v for the device is below. I tested the device
> with MacOSX and found a transfer rate corresponding to high-speed
> (approximately the same as for a nicely working USB key, see below).
>
> In the meantime, I have tested the device with a different linux
> computer (also debian lenny) and found the same transfer rates. Only,
> this time the companion driver is UHCI and not OHCI. The logs below
> correspond to this situation.
I don't know what's going on with your Mac OSX test; however the lsusb
output indicates plainly that the Samsung device does not run at high
speed. The key point is lack of a Device Qualifier descriptor -- it
is mandatory for high-speed devices (and notice that it is present in
the working Toshiba device).
Could it be that the Samsung device runs at full speed even under OSX
and somehow your transfer rate test is giving a misleading result?
> > Another possible explanation is that your computer's EHCI controller
> > doesn't work properly. Can you run any devices attached to that USB
> > port at high speed?
>
> Yes, I can. For comparison, I include the output from lsusb -v for a
> Toshiba USB key, which works nicely.
If you want a definitive test then edit the kernel source file
drivers/usb/host/ehci_hub.c, and at the start of the
check_reset_complete() routine add the following lines:
ehci_dbg(ehci, "port %d status after reset 0x%x\n",
index + 1, port_status);
After you build and load the new ehci_hcd.ko module, that new debugging
line should show up in the dmesg log when you plug in any USB device.
What does it say for the Samsung and Toshiba devices?
Alan Stern
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