From owner-freebsd-hardware Mon Apr 15 10:47:41 2002 Delivered-To: freebsd-hardware@freebsd.org Received: from wartch.sapros.com (rularan.sapros.com [204.182.55.17]) by hub.freebsd.org (Postfix) with ESMTP id 7238437B405 for ; Mon, 15 Apr 2002 10:47:37 -0700 (PDT) Received: from wartch.sapros.com (localhost.sapros.com [127.0.0.1]) by wartch.sapros.com (8.12.1/8.12.1) with ESMTP id g3FHlPRg037046; Mon, 15 Apr 2002 10:47:25 -0700 (PDT) (envelope-from peterh@wartch.sapros.com) Message-Id: <200204151747.g3FHlPRg037046@wartch.sapros.com> To: Nick Hibma Cc: hardware@freebsd.org Subject: Re: Reading from the USB ugen device. Date: Mon, 15 Apr 2002 10:47:25 -0700 From: Peter Haight X-Spam-Status: No, hits=1.8 required=7.0 tests=NO_MX_FOR_FROM version=2.11 Sender: owner-freebsd-hardware@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org >> From what you told me and a brief look at the USB spec, I'm guessing it >> isn't a coincidence that it is failing on that read where I'm expecting 64 >> bytes (the max size of a USB packet payload). I'm guessing that in short >> read mode, the driver gets a full length packet and is expecting another >> data packet but it never comes because that's the end of the data, so it >> doesn't return from the read until it gets a timeout. > >No. If you read 64 byes in 64 bytes with short_XFER switched on you will >be reading 64 bytes and then 0 bytes. Ok. But why does this happen: read(3, 0x8091800, 1024) read -1 bytes At that same point in the protocol if I do: read(3, 0x8091800, 64) read 64 bytes I would expect: read(3, 0x8091800, 1024) read 64 bytes To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hardware" in the body of the message