On Thu, 20 Dec 2007, Matthias Schniedermeyer wrote:
> On 20.12.2007 11:42, Alan Stern wrote:
> > On Thu, 20 Dec 2007, Matthias Schniedermeyer wrote:
> >
> > > This is interesting, i pluged the (High-Speed-)HUB with the Low-Speed
> > > peripherals into another root-port. How can it be that this brings down
> > > the WHOLE usb subsystem, the computer that i replaced with this machine
> > > only had an USB-OHCI controller onboard, so i plugged the HDD into an
> > > add-on USB-controller and the same(!) low-speed devices where driven by
> > > the OHCI-driver?
> >
> > It doesn't bring down the whole USB subsystem. You are overreacting to
> > the volume of messages in the system log. All that went down was the
> > high-speed hub -- but of course when the hub went down it took along
> > the various devices plugged into it.
>
> The HDD isn't connected to an (addional) Hub, only the low-speed
> devices. And the low-speed devices are only present and not in "active"
> use while i copy something to the HDD.
>
> So can i assume that you suggest i should try some other hub for my
> low-speed devices?
It's worth a try. For instance, a full-speed (USB 1.1) hub wouldn't
have these problems.
Here's another idea: You can force your current hub to run at full
speed instead of high speed. You won't lose any performance, because
the devices attached to the hub don't run at high speed anyway. The
advantage is that when you do this, the hub will be on a different bus
from the disk drive. There shouldn't be any interference between them.
As I recall from your logs, the hub is attached to port 4 on bus 7.
To force it into full speed, all you have to do is:
echo 4 >/sys/class/usb_host/usb_host7/companion
Unfortunately this setting will go away every time you reboot, so you
would need to add it to a startup script.
Alan Stern
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