On Fri, May 21, 2004 at 05:52:37PM -0400, Alan Stern wrote:
> Greg:
> 
> This patch reads the full 9 bytes of a configuration descriptor during 
> enumeration rather than just the first 8 bytes.  That's how Windows does 
> it, and today I ran across a device that doesn't work properly when asked 
> to send only 8 bytes worth.  I doubt very much this will cause any 
> problems with currently-working devices; since the descriptor itself is 9 
> bytes long and since the devices are most likely to expect a 9-byte 
> request, anything that can handle an 8-byte request should have no 
> difficulty.  (Also, some debugging messages have been slightly improved.)
> 
> Please apply.

Applied, thanks.

> Incidentally, USB traces taken from Windows 2000 and Windows XP show that
> when those operating systems retrieve a string descriptor during
> enumeration, they do so by requesting a 255-byte transfer.  They do not
> first ask just for the initial 2 bytes (which contain the actual length)  
> and then ask for the actual length, which is what we do.  Interestingly,
> back in 2.4 we _did_ do things the same as Windows.

Yeah, I remember that we changed this, but I don't remember why we did
so.  I think because that was the way Win98 used to work.  Anyone else
recall?

thanks,

greg k-h


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