On Fri, 9 Jul 2004, Matthew Dharm wrote:
> But, sometime later, we get:
>
> > Jul 9 16:03:31 asengard usb-storage: Bulk Status S 0x53550000 T
> > 0x4405342 R 0 Stat 0x0
> > Jul 9 16:03:31 asengard usb-storage: Bulk logical error
>
> And this is not good. In fact, it looks like the USB packet has been very
> badly corrupted. The first value there should be 0x53425355 -- to me, it
> looks like several bytes in the packet have been swapped around (or perhaps
> just pushed around out of alignment?). The tag is scrambled also (it
> should be 0x440).
Apparently two bytes of zeros were inserted at the beginning of the
packet. The structure of the packet (LSB first, the way it's
transmitted) looks like this:
Signature Tag Residue
----------- ----------- -----------
Ought to be: 55 53 42 53 40 04 00 00 00 00 00 00
Actually was: 00 00 55 53 42 53 40 04 00 00 00 00
> Given this input, the driver declares a logical error
> and follows the required reset procedure.
>
> The good news: the reset procedure worked (eventually) and your system
> didn't crash.
Actually that's quite good. Until very recently the USB reset code wasn't
working right.
It's worth mentioning that in all the error logs reported by various users
over the years, the device reset step of the error recovery procedure
almost never works. Maybe we should skip it and always proceed directly
to the bus reset step?
> The bad news: this should have never happened in the first place.
>
> My top two guesses:
> (1) HCD bug
> (2) oddly broken hardware
It's extremely unlikely to be a software bug in the host controller
driver. Unless something _very_ bizarre is happening, this is a hardware
bug either in the controller or in the device. The easiest way to test is
to try using another device, and to try using this device on another Linux
computer (or even on another port on the same computer).
Alan Stern
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