Re: [PATCH] usb: gadget: storage: check for valid USB_BULK_GET_MAX_LUN_REQUEST

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On Fri, 14 Oct 2011, Felipe Balbi wrote:

> On Thu, Oct 13, 2011 at 09:42:40PM -0400, Alan Stern wrote:
> > On Thu, 13 Oct 2011, Paul Zimmerman wrote:
> > 
> > > The latest USB-IF CV tester checks for a valid length for this
> > > request.
> > 
> > That's dumb.  The BOT spec doesn't say anything about what a device
> > should do if it receives a request with wLength > 1.  Therefore it's
> > wrong to say that a device is non-compliant with the spec if it replies
> > to such requests.
> > 
> > If anything, this should be a test of the host, not of the device.  
> > After all, it's the host's fault if wLength is set to the wrong value.
> > 
> > Instead of changing this, I'd prefer to complain to the USB-IF.
> 
> It's the same with SetAddress command. A SetAddress() on Configured
> state has unspecified answer, nevertheless USB-IF is very, very bad at
> changing those Command Verifier tools and every time I have tried
> reporting a bug (either on Windows Stack or Command Verifier Stack) they
> always reply with the same stock answer: "Other devices have passed
> certification on the same setup, so why can't you?"
> 
> That means the USB Certified sticker has nothing to do with being
> compliant with the Spec, rather being compliant with Windows.
> 
> On top of all that, if we don't apply this there will be a big number of
> Linux devices which will have to keep this patch on their own out of
> tree queue just to pass certification.
> 
> Do we want that ? I think it's far better to apply this patch, but mark
> it as host-side quirk or something. The host stack has quirks for
> out-of-spec devices, why can't the device stack have quirk for
> out-of-spec hosts ?

All right, I withdraw any objection to the patch.  However, I'd like to
point out that this isn't a quirk for out-of-spec hosts; the existing
code already works perfectly well with hosts that send these
out-of-spec requests.  Rather, it's a quirk for an out-of-spec CV test.

Alan Stern

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