From owner-freebsd-hardware  Wed Apr 17 23: 4:54 2002
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Date: Thu, 18 Apr 2002 16:04:31 +1000 (EST)
From: Bruce Evans <bde@zeta.org.au>
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To: Nick Hibma <n_hibma@van-laarhoven.org>
Cc: Peter Haight <peterh@sapros.com>, <hardware@FreeBSD.ORG>
Subject: Re: Reading from the USB ugen device. 
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On Wed, 17 Apr 2002, Nick Hibma wrote:

> > Here the problem may be the more immediate one that usb returns EIO
> > instead of EWOULDBLOCK when it can't proceed.
>
> EIO is only returned in case of error. I was mistaken. EWOULDBLOCK can never
> be returned because the ugen driver can't know whether or no the transfer is
> going to block. There is no such thing as a poll for data on the USB bus.

It seems to sometimes return ETIMEDOUT, which causes the same problem.

Bruce


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