From owner-freebsd-hackers@FreeBSD.ORG Wed Jun 25 11:58:36 2003 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id BFB3237B401 for ; Wed, 25 Jun 2003 11:58:36 -0700 (PDT) Received: from whizzo.transsys.com (whizzo.TransSys.COM [144.202.42.10]) by mx1.FreeBSD.org (Postfix) with ESMTP id 08ACB43FBF for ; Wed, 25 Jun 2003 11:58:36 -0700 (PDT) (envelope-from louie@whizzo.transsys.com) Received: from whizzo.transsys.com (#6@localhost [127.0.0.1]) by whizzo.transsys.com (8.12.9/8.12.9) with ESMTP id h5PIwSW8017536; Wed, 25 Jun 2003 14:58:28 -0400 (EDT) (envelope-from louie@whizzo.transsys.com) Message-Id: <200306251858.h5PIwSW8017536@whizzo.transsys.com> X-Mailer: exmh version 2.6.3 04/04/2003 with nmh-1.0.4 To: "M. Warner Losh" X-Image-URL: http://www.transsys.com/louie/images/louie-mail.jpg From: "Louis A. Mamakos" References: <20030625.101549.78767546.imp@bsdimp.com> In-reply-to: Your message of "Wed, 25 Jun 2003 10:15:49 MDT." <20030625.101549.78767546.imp@bsdimp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Wed, 25 Jun 2003 14:58:28 -0400 Sender: louie@TransSys.COM cc: freebsd-hackers@freebsd.org Subject: Re: USB, select/poll for ucom X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 25 Jun 2003 18:58:37 -0000 > In message: > Danny Braniss writes: > : > : > I'm able to use ppp with umodem/ucom. My brother uses ulpcom/ucom for > : > his ppp needs. I'm pretty sure that select is involved. :-) > : > > : > >From what I can see in the code, I'd expect that it would work because > : > the ttypoll routine is specified for the poll routine. Why do you > : > think it wouldn't work? > : > : well, for one, my program doesn't work :-), it works with the RS232 version. > : > : so i started to poke around, and did some reading, and as far as i could tell, > : the read(2) has to be initiated by the host, but my knowledge of usb is close > : to zero - it was zero 2 days ago, but still looking for some better docs, and > : polish my english - as far as i remember interrupt is not polling, but the > : ohci docs imply that :-) > > have fun. the mindshare book is good. however, it took me a long > time to get a usb 'aha' moment and understand its twisty maze was > really a workable design obscured by standardese... I suspect it is a > problem in the usb chipset driver for the com part. ttypoll just says > 'you have data in the buffer' so for some reason the data isn't making > into the tty buffer. I think the problem is that the USB hardware doesn't try to read data from the peripheral until the user-mode code does a read(2) system call. I had this problem with the ugen device. I would guess that the ucom/umodem devices could use the tty clist infrastructure as the intermediate buffer for data to be stuck into absent the user application doing a read. louie