From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from pentafluge.infradead.org (pentafluge.infradead.org [213.146.154.40]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTP id A6AE8DDF0F for ; Wed, 4 Apr 2007 09:29:17 +1000 (EST) Subject: Re: [PATCH] Stop pmac_zilog from abusing 8250's device numbers. From: David Woodhouse To: Paul Mackerras 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 Cc: linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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