Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 14 Mar 2003 18:52:02 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 14 Mar 2003 18:52:02 -0500 Received: from h-64-105-35-119.SNVACAID.covad.net ([64.105.35.119]:46475 "EHLO freya.yggdrasil.com") by vger.kernel.org with ESMTP id ; Fri, 14 Mar 2003 18:52:01 -0500 From: "Adam J. Richter" Date: Fri, 14 Mar 2003 16:02:38 -0800 Message-Id: <200303150002.QAA01487@adam.yggdrasil.com> To: rmk@arm.linux.org.uk Subject: Re: devfs + PCI serial card = no extra serial ports Cc: driver@jpl.nasa.gov, dwmw2@infradead.org, EdV@macrolink.com, linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2919 Lines: 54 On Fri, 14 Mar 2003, Russell King wrote: >On Fri, Mar 14, 2003 at 12:28:47PM -0800, Adam J. Richter wrote: >> There was tangential mention in that thread >> of a "/proc/serialdev" interface, but nobody really identified any >> real benefit to it over the existing "uart: unknown" system. >There is one benefit, which would be to get rid of some of the yucky >mess we currently have surrounding the implementation of stuff which >changes the port base address/irq. >Currently, we have to check that we're the only user, shutdown, tweak >stuff, hope it all goes to plan, and start stuff back up again. If >something fails, we have to pray we can go back to the original setup >without stuff breaking. If that fails, we mark the port "unknown". >All of this would be a lot simpler if we didn't have the port actually >open at the time we change these parameters. We could just lock the >port against opens, check no one was using it, tweak the settings, >and release the port. If the changes fail, just report the failure. When I filter out prejudicial terminology like "yucky mess", "pray", "just", etc., I don't see a convincing explanation of how one approach is going to result in a lower line count, fewer branches, smaller kernel footprint, faster execution, new capabilities or any other relevant measure that I can think of in comparison to the existing approach. As far as only one user having the port open when doing an ioctl to define the port, it is not clear to me that a /proc-like interface would do it in less code. Given that you still have the possibility of undefining serial ports on the system, the issue of making sure that there is only one user with the port open in the case of deletion should still be approximately the same under either approach. Perhaps I'm talking this to death. Maybe if you post a diff that is a net reduction of lines of code, that would clarify things more easily than discussing it further before that point. Anyhow, I'm not involved in serial driver development. I just think that if we try to avoid prejudicial language, we're more likely to make more better decisions by whatever measures we agree on (or expose differences in what is "better" in different contexts). I know it's a pain to do and I'm not trying to create an infinitely high standard of proof or formality. I'm just suggesting a little more checking of our own objectivity. Adam J. Richter __ ______________ 575 Oroville Road adam@yggdrasil.com \ / Milpitas, California 95035 +1 408 309-6081 | g g d r a s i l United States of America "Free Software For The Rest Of Us." - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/