From owner-freebsd-current@FreeBSD.ORG  Tue Sep  5 19:09:14 2006
Return-Path: <owner-freebsd-current@FreeBSD.ORG>
X-Original-To: freebsd-current@freebsd.org
Delivered-To: freebsd-current@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id 94E5216A501;
	Tue,  5 Sep 2006 19:09:14 +0000 (UTC) (envelope-from imp@bsdimp.com)
Received: from harmony.bsdimp.com (vc4-2-0-87.dsl.netrack.net [199.45.160.85])
	by mx1.FreeBSD.org (Postfix) with ESMTP id 542E943D53;
	Tue,  5 Sep 2006 19:04:27 +0000 (GMT) (envelope-from imp@bsdimp.com)
Received: from localhost (localhost.village.org [127.0.0.1] (may be forged))
	by harmony.bsdimp.com (8.13.4/8.13.4) with ESMTP id k85J2TUU014641;
	Tue, 5 Sep 2006 13:02:30 -0600 (MDT) (envelope-from imp@bsdimp.com)
Date: Tue, 05 Sep 2006 13:02:47 -0600 (MDT)
Message-Id: <20060905.130247.-267228160.imp@bsdimp.com>
To: phk@phk.freebsd.dk
From: "M. Warner Losh" <imp@bsdimp.com>
In-Reply-To: <14026.1157478288@critter.freebsd.dk>
References: <20060905173334.GH9421@funkthat.com>
	<14026.1157478288@critter.freebsd.dk>
X-Mailer: Mew version 4.2 on Emacs 21.3 / Mule 5.0 (SAKAKI)
Mime-Version: 1.0
Content-Type: Text/Plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-2.0
	(harmony.bsdimp.com [127.0.0.1]);
	Tue, 05 Sep 2006 13:02:31 -0600 (MDT)
Cc: gurney_j@resnet.uoregon.edu, freebsd-current@freebsd.org,
	freebsd-drivers@freebsd.org, freebsd-arch@freebsd.org
Subject: Re: bus_get_dma_tag now necessary for drivers using bus_dma 
X-BeenThere: freebsd-current@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Discussions about the use of FreeBSD-current
	<freebsd-current.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>, 
	<mailto:freebsd-current-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-current>
List-Post: <mailto:freebsd-current@freebsd.org>
List-Help: <mailto:freebsd-current-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>,
	<mailto:freebsd-current-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Tue, 05 Sep 2006 19:09:14 -0000

In message: <14026.1157478288@critter.freebsd.dk>
            "Poul-Henning Kamp" <phk@phk.freebsd.dk> writes:
: In message <20060905173334.GH9421@funkthat.com>, John-Mark Gurney writes:
: 
: >This means that for each call to bus_dma_tag_create, instead of passing
: >a NULL pointer, you should call bus_get_dma_tag(yourdev) and use that
: >as the parent tag.  I committed some example code to various drivers,
: >such as ahc, ata, em, and ohci.
: 
: If there are never any exeptions to this requirement, why not
: pass "yourdev" and have the magic hidden, rather than add 17
: ritual characters to the API ?

As Scott pointed out, it won't always be NULL.  I like his idea of
having a variant that takes a device_t...

Warner