On Wed, May 05, 2004 at 01:02:59PM -0600, Pat LaVarre wrote: > > > Usb-storage in particular needs this, > > > because a number of storage devices can't > > > handle ordinary USB requests (like > > > GET_DESCRIPTOR) while processing a SCSI > > > command. It's not clear whether or not this > > > is in violation of the USB spec, but that's > > > the way they are. Hotplug scripts in > > > particular can generate usbfs activity that > > > interferes with the devices' operation. > > > > ... I believe (and the folks on the USB-IF that > > I've spoken to all agree) that this is a clear > > spec violation. > > I agree in 1998 everyone was supposed to understand this taboo. > > But I don't find any citations of specifically relevant English. So far > as I know, this violation is so creative as to not have been > anticipated, thus never explicitly outlawed.
I believe it is outlawed by a section of the USB core specification which
requires all devices to be able to accept 'ordinary' control-endpoint
requests at "all times".
> The new bco msc (binary code only, mass storage committee) compliance
> test should check for this violation. I expect it won't unless someone
> volunteers to help it (e.g. by making pass thru to USB from the Linux
> command line easy).
Use libusb. Remember to unload usb-storage first. Then, send 2 URBs --
the first one a CSW for something that will exchange data, and the second a
get string descriptor request.
Matt
--
Matthew Dharm Home: [EMAIL PROTECTED]
Maintainer, Linux USB Mass Storage Driver
Somebody call an exorcist!
-- Dust Puppy
User Friendly, 5/16/1998
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