On Fri, 1 Feb 2008, Matthew Dharm wrote:

> On Fri, Feb 01, 2008 at 10:17:24AM -0500, Alan Stern wrote:
> > On Thu, 31 Jan 2008, David Brownell wrote:
> > 
> > > On Thursday 31 January 2008, Alan Stern wrote:
> > > > The interesting difference lay in what Windows did when the Get-Max-LUN 
> > > > stalled.  It sent a Clear-Halt request to endpoint 0!
> > > 
> > > Yes that *is* strange!  Considering that ep0 wasn't stalling ...
> > 
> > No, ep0 did stall (at least, that's the way it looks from the SnoopyPro
> > trace and that's what happened under Linux).  This was in response to
> > the Bulk-only-transport class-specific Get-Max-LUN request.  Devices
> > are permitted not to support that request if they have only one LUN.
> > 
> > Right now usb-storage responds to this stall by clearing the halt 
> > feature from the bulk-in and bulk-out endpoints, not because the spec 
> > says to do so but because one ancient device (a ZIP-100) requires it.  
> > Now it looks as though we've found a device which can't handle it.  
> > Time for another quirk?
> 
> Do we really need another quirk?  If the 'popular' OS does it, it's likely
> safe to do for all deveices when GetMaxLUN fails...

You missed the point.  Windows does _not_ do it -- i.e., does not clear 
a halt on either bulk endpoint.  Linux does so only because somebody 
(either Pete Zaitcev or Pat Lavarre, I can't remember which) pointed 
out that the ZIP-100 drive needs it.

The clear-halt for endpoint 0 probably isn't needed by anything; I
don't know why Windows does it.

Alan Stern

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