From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754058AbZBDH5q (ORCPT ); Wed, 4 Feb 2009 02:57:46 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751918AbZBDH5g (ORCPT ); Wed, 4 Feb 2009 02:57:36 -0500 Received: from smtp-out002.kontent.com ([81.88.40.216]:42555 "EHLO smtp-out002.kontent.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751513AbZBDH5f (ORCPT ); Wed, 4 Feb 2009 02:57:35 -0500 From: Oliver Neukum Organization: Novell To: Greg KH Subject: Re: [stable] A patch in 2.6.27.9 caused device names to change Date: Wed, 4 Feb 2009 08:28:44 +0100 User-Agent: KMail/1.9.10 Cc: Dan Williams , Chuck Ebbert , linux-kernel@vger.kernel.org, stable@kernel.org References: <20090202170238.348af36a@dhcp-100-2-144.bos.redhat.com> <1233672611.11344.6.camel@localhost.localdomain> <20090204000342.GB22380@kroah.com> In-Reply-To: <20090204000342.GB22380@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200902040828.45615.oliver@neukum.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am Wednesday 04 February 2009 01:03:42 schrieb Greg KH: > On Tue, Feb 03, 2009 at 09:50:11AM -0500, Dan Williams wrote: > > For a long time we've been operating under the assumption that mobile > > broadband devices should be driven by option and sierra, since those > > drivers had the necessary buffering optimizations to support > > higher-speed mobile broadband devices. > > Who is "we" here? Not me :) We currently have three drivers that can handle high speed serial connections in USB, option, sierra and cdc-acm. > > That was true at least up until 2.6.24. > > It all depends on the type of device. If it says it is a cdc-acm modem, > by all means, let that driver handle it, don't try to bind it to a > different driver (that way lies races and madness...) > > > Furthermore, up until this point, I have not seen mobile broadband > > adapters (that aren't cellphones connected via USB) that *are* CDC-ACM > > compliant. Everything previously has advertised proprietary interfaces, > > some of which are serial ports and some of which are not. > > Probably because we never see those devices being reported, because they > "just work" with no interaction from us. As far as I can tell, devices implementing the class specification are new and still quite rare. This is probably related to the relative newness of the WHC specification. > > Plus, are we expected to keep device names stable these days? cdc-acm > > is the catch-all driver, but if that driver is more "generic" and a > > better driver is found, can we not update IDs just because the device > > name may change? There is no such thing as a better driver for a device that correctly implements the class specification than the class driver. You haven't seen complaints about cdc-acm's performance in a long time, have you? Regards Oliver