8.0-RC USB/FS problem

Guojun Jin gjin at ubicom.com
Wed Dec 2 19:27:30 UTC 2009

I noticed that your machine also has an AMD CPU. Hopefully this may NOT
imply something to the hardware.

I will find more systems especially Intel CPUs to do further test.

-----Original Message-----
From: Stefan Esser [mailto:se at freebsd.org] 
Sent: Monday, November 30, 2009 12:18 PM
To: Hans Petter Selasky
Cc: freebsd-usb at freebsd.org; bugs at freebsd.org;
freebsd-stable at freebsd.org; Guojun Jin
Subject: Re: 8.0-RC USB/FS problem

On 22.11.2009 10:47 Hans Petter Selasky wrote:
> Other operating systems do a port bus reset when the device has a
problem. On 
> FreeBSD we just try a software reset via the control endpoint. I guess
that it 
> is a device problem you are seeing. The USB stack in FreeBSD is faster
> the old one, and maybe the faster queueing of mass storage requests
> some hidden bugs in your device.
> When the problem happens try:
> sysctl hw.usb.umass.debug=-1

I have observed USB lock-ups with several external drive enclosures
that used to work with the old USB stack (and continue to work when
connected to a Windows notebook, for example). (BTW: System is AMD X2
with Nvidia chip-set and i386 kernel.)

In my case, hw.usb.debug=6 makes the drive work at some 4MB/s for
any amount of data transfered, while hw.usb.debug=5 (and an ylower
value) lets the drive pause for about 1 Minute per 100MB transfered.
I wanted to test whether short delays inserted in the places with
DPRINTFN(6, ...) make a difference, but will not get to it before
the weekend.

Regards, STefan

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