From owner-freebsd-hackers Mon Feb 11 13:15:27 2002 Delivered-To: freebsd-hackers@freebsd.org Received: from mass.dis.org (adsl-64-173-25-69.dsl.sntc01.pacbell.net [64.173.25.69]) by hub.freebsd.org (Postfix) with ESMTP id E33B437B417; Mon, 11 Feb 2002 13:15:11 -0800 (PST) Received: from mass.dis.org (localhost [127.0.0.1]) by mass.dis.org (8.11.6/8.11.6) with ESMTP id g1BLDL201611; Mon, 11 Feb 2002 13:13:22 -0800 (PST) (envelope-from msmith@mass.dis.org) Message-Id: <200202112113.g1BLDL201611@mass.dis.org> X-Mailer: exmh version 2.5 07/13/2001 with nmh-1.0.4 To: j mckitrick Cc: freebsd-hackers@freebsd.org, freebsd-newbus@freebsd.org Subject: Re: Adding newbus abstraction to parallel port devices In-reply-to: Your message of "Mon, 11 Feb 2002 13:41:43 GMT." <20020211134143.A24762@dogma.freebsd-uk.eu.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Mon, 11 Feb 2002 13:13:21 -0800 From: Michael Smith Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG > last time I looked, the parallel port chipset driver (isa/ppc) uses > microsequences to handle the hardware control/data ports for the > parallel port. For anyone who is unfamiliar with these, they are macros > built from I/O port bitmasks to handle the necessary hardware > control to run the parallel port. > > The committer that wrote the parallel port driver said he used > microsequences because the driver was designed/implemented before > newbus. > > Since the purpose of the microsequences was (a) hardware abstraction and > (b) to increase speed, how could this be re-written to use newbus > instead without a performance loss? You wouldn't want to. I devised the microsequence mechanism (which Nicholas greatly expanded and actually implemented) to get around the problem whereby a peripheral driver knows what the hardware needs to do, but does not know how to make the hardware do it. This is orthogonal to newbus, which provides glue for building the device tree and the like. Regards, Mike -- To announce that there must be no criticism of the president or that we are to stand by the president right or wrong is not only unpatriotic and servile, but is morally treasonable to the American public. - Theodore Roosvelt To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message