From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1946035AbXDCX3S (ORCPT ); Tue, 3 Apr 2007 19:29:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1946034AbXDCX3S (ORCPT ); Tue, 3 Apr 2007 19:29:18 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:52074 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1946035AbXDCX3S (ORCPT ); Tue, 3 Apr 2007 19:29:18 -0400 Subject: Re: [PATCH] Stop pmac_zilog from abusing 8250's device numbers. From: David Woodhouse To: Paul Mackerras Cc: linuxppc-dev@ozlabs.org, benh@kernel.crashing.org, linux-kernel@vger.kernel.org In-Reply-To: <17938.57292.870224.132415@cargo.ozlabs.ibm.com> References: <1175610345.2665.15.camel@shinybook.infradead.org> <17938.57292.870224.132415@cargo.ozlabs.ibm.com> Content-Type: text/plain Date: Tue, 03 Apr 2007 19:28:36 -0400 Message-Id: <1175642916.10567.24.camel@shinybook.infradead.org> Mime-Version: 1.0 X-Mailer: Evolution 2.10.0 (2.10.0-7.fc7.dwmw2.2) Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2007-04-04 at 09:14 +1000, Paul Mackerras wrote: > Sigh. I guess this is inevitable, but IMNSHO this exposes a weakness > in our serial subsystem. > > The problem is that this means that a user has to know "oh, the serial > port on my computer is implemented with a Z85C30 chip, therefore it's > /dev/ttyPZ0 not /dev/ttyS0, like it would be if the designers had used > a 16C550". > > Plus I'm sure this is going to mean that people using gui ppp dialers > on powermacs will suddenly find that the gui can no longer find their > serial port and they have no idea why. > Why should a user know or care about that? It really should be "it's > the built-in serial port on my computer therefore it's /dev/ttyS0". I agree to a certain extent -- but then again, why should a user know or care about the name /dev/ttyS0 _either_? A GUI PPP dialer should be listing the available serial ports in the system whatever their names are. And nobody _forces_ you to use the name ttyPZ0. If you really want, you can call it ttyS0.... just mknod /dev/ttyS0 204 192 You could even have udev rules which share the /dev/ttyS$N namespace between _all_ kinds of serial ports, if you really want to. Abusing the 8250 device numbers prevents the 8250 module from being loaded at the same time as pmac_zilog, and means you can't have both internal port and PCMCIA or PCI 8250 ports active at the same time. -- dwmw2