From owner-freebsd-usb@FreeBSD.ORG Sat Jun 17 17:15:58 2006 Return-Path: X-Original-To: freebsd-usb@freebsd.org Delivered-To: freebsd-usb@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 2BB9B16A479 for ; Sat, 17 Jun 2006 17:15:58 +0000 (UTC) (envelope-from hselasky@c2i.net) Received: from mail45.e.nsc.no (mail45.e.nsc.no [193.213.115.45]) by mx1.FreeBSD.org (Postfix) with ESMTP id 9A06843D45 for ; Sat, 17 Jun 2006 17:15:57 +0000 (GMT) (envelope-from hselasky@c2i.net) Received: from Unknown-00-c0-9f-49-78-d8.lan (ti131310a080-6417.bb.online.no [85.165.217.17]) by mail45.nsc.no (8.13.6/8.13.5) with ESMTP id k5HHFsLL026466; Sat, 17 Jun 2006 19:15:55 +0200 (CEST) From: Hans Petter Selasky To: Anish Mistry Date: Sat, 17 Jun 2006 19:15:58 +0200 User-Agent: KMail/1.7 References: <200606161724.21722.mistry.7@osu.edu> <200606170950.10062.hselasky@c2i.net> <200606171154.50869.mistry.7@osu.edu> In-Reply-To: <200606171154.50869.mistry.7@osu.edu> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200606171916.00064.hselasky@c2i.net> Cc: freebsd-usb@freebsd.org Subject: Re: ugen partial write() amount X-BeenThere: freebsd-usb@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: FreeBSD support for USB List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 17 Jun 2006 17:15:58 -0000 On Saturday 17 June 2006 17:54, Anish Mistry wrote: > On Saturday 17 June 2006 03:50, Hans Petter Selasky wrote: > > On Friday 16 June 2006 23:24, Anish Mistry wrote: > > > I'm trying to reliably recover from a write() timeout using > > > ugen. The problem that I'm having is that when using write() to > > > write data to an endpoint and the write times out there seems no > > > way to figure out the amount of that data that was actually > > > written. This is a problem when trying to write data to a > > > printer and the paper runs out. write() will timeout and you are > > > left with no way to figure out where to start sending data since > > > you don't know how much was received by the device before the > > > paper ran out. > > > It seems this could be possible by modifying the driver by > > > adding and ioctl that would allow you to call bulk transfer and > > > then return the number of bytes written. Is there a better way > > > of doing? > > > > What about disabling the timeout ? > > That works, the problem is that the write() will block causing the > controller application to be non-responsive and not report the > condition that caused the failure since it has blocked. I have some plans to make "ugen" asynchronous. Then you can use FIONBIO to set non-blocking mode, and poll the file descriptor. That is the solution I see. > My conclusion so far is that I would need to thread the writing logic > in the application, and then write my own timeout logic when I notice > that the write is blocking for longer than our time interval. At > least that is the option I can think of without modifying the driver. Yes. --HPS