From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757272AbbAHWFg (ORCPT ); Thu, 8 Jan 2015 17:05:36 -0500 Received: from mout.kundenserver.de ([212.227.17.24]:50079 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753677AbbAHWFe (ORCPT ); Thu, 8 Jan 2015 17:05:34 -0500 From: Arnd Bergmann To: Peter Hurley Cc: One Thousand Gnomes , Greg Kroah-Hartman , Jiri Slaby , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Sebastian Andrzej Siewior , Tony Lindgren , Grant Likely Subject: Re: [PATCH] serial: 8250: Make ISA ports optional Date: Thu, 08 Jan 2015 23:05:12 +0100 Message-ID: <1896224.oMI8M6J5T7@wuerfel> User-Agent: KMail/4.11.5 (Linux/3.16.0-10-generic; KDE/4.11.5; x86_64; ; ) In-Reply-To: <54AEAC47.1040403@hurleysoftware.com> References: <1420513785-23660-1-git-send-email-peter@hurleysoftware.com> <20150108131008.16c9a31c@lxorguk.ukuu.org.uk> <54AEAC47.1040403@hurleysoftware.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Provags-ID: V03:K0:zYqUSBrBS6uCLv29FQcr5J6Q/SP3kTaoAZ2H2kFawLhQ9DfliTg Jk3aY5KxHdOMq+ZhqfPcn0GHNhXY1cbrhaXVEy33uB3YngLEBKgeQlnElwJ/lXUWrrDjEwn dW1dqai3z/0MKX4fz54sZ+gVhzXq4C4BW5YDsluXYau8sEBpLHSq5FZKutxAGrYmsFzyboA hWbpsIjmc1/qrSu0FNQLQ== X-UI-Out-Filterresults: notjunk:1; Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 08 January 2015 11:11:51 Peter Hurley wrote: > > This interface is just storage and minor allocation, since the > port-reuse behavior will be limited to the "universal" driver. > From a sub-driver perspective, the shared storage is actually > a hindrance, so that reduces the requirement to minor allocation. > > And that's where I'm stuck at the moment -- how to share ttyS > minor allocation. ttyS console is a related problem. One idea that has come up in the past but never saw an implementation is to make the ttyS namespace and minor numbers completely generic and let any serial port driver use it. This would be a major rework, but have the added advantage of cleaning up a number of other namespace issues as well. There also lots of open question, in particular how to maintain compatibility with existing drivers. One could imagine that each uart always gets a ttyS device and optionally also gets a device node for the same port with a driver specific chardev as most of them do today. Or it could be an either/or decision that is made at compile time or as a module parameter. Arnd