Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753453Ab0ATRPP (ORCPT ); Wed, 20 Jan 2010 12:15:15 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753300Ab0ATRPN (ORCPT ); Wed, 20 Jan 2010 12:15:13 -0500 Received: from mail-bw0-f227.google.com ([209.85.218.227]:45182 "EHLO mail-bw0-f227.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753187Ab0ATRPL convert rfc822-to-8bit (ORCPT ); Wed, 20 Jan 2010 12:15:11 -0500 MIME-Version: 1.0 In-Reply-To: <4B573501.9090001@jic23.retrosnub.co.uk> References: <4B571DA4.6070603@cam.ac.uk> <20100120153748.GA29401@kroah.com> <4B573501.9090001@jic23.retrosnub.co.uk> From: Kay Sievers Date: Wed, 20 Jan 2010 18:14:54 +0100 Message-ID: Subject: Re: [RFC] Staging:IIO: New ABI To: Jonathan Cameron Cc: Greg KH , Jonathan Cameron , LKML , Manuel Stahl , "Hennerich, Michael" , "Frysinger, Michael" , "Getz, Robin" , Jean Delvare , "Trisal, Kalhan" , "Zhang, Xing Z" , Ira Snyder Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1648 Lines: 36 On Wed, Jan 20, 2010 at 17:53, Jonathan Cameron wrote: >>> What:                /sys/.../ring_buffer[m]/ring_event[o]/dev >>> Description: >>>              Ring buffer m event character device o major:minor numbers. >> >> Again, don't bury devices.  Or if you are, use a bus, not a class, >> that's the wrong classification. > Cool, I'll look into making the change.  What we really have here > is a single conceptual device using a pair or character interfaces.  Is a bus > the right way to handle that? "bus" and "class" are almost the same regarding the driver core, it should not make any difference for you. The "class" implementation is only a very simple case of a "bus" -- just with a pretty much broken userspace interface. :) Today, if we would start from scratch, there would be only something like /sys/subsystem in the layout of today's /sys/bus, and /sys/class, /sys/bus and /sys/block would not event exist. Tools like udev intentionally make no difference between them, and do not allow to distinguish between "class" or "bus". It's just called "susbsystem" there from the early days on. The "class" has only a single flat directory in /sys so it can never be extended with anything custom. No new subsystem should use the class interface anymore, all should use a "bus". I guess it's time to document that somewhere. :) Thanks, Kay -- 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/