From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oliver Neukum Subject: Re: [PATCH] USB host CDC Phonet network interface driver Date: Fri, 24 Jul 2009 18:59:17 +0200 Message-ID: <200907241859.17883.oliver@neukum.org> References: <1248177515-12712-1-git-send-email-remi.denis-courmont@nokia.com> <200907241612.41871.oliver@neukum.org> <20090724151941.40dba19d@lxorguk.ukuu.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Cc: "=?iso-8859-1?q?R=E9mi?= Denis-Courmont" , Marcel Holtmann , ext Dan Williams , "netdev@vger.kernel.org" , "linux-usb@vger.kernel.org" To: Alan Cox Return-path: Received: from smtp-out003.kontent.com ([81.88.40.217]:55474 "EHLO smtp-out003.kontent.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753833AbZGXSoK (ORCPT ); Fri, 24 Jul 2009 14:44:10 -0400 In-Reply-To: <20090724151941.40dba19d@lxorguk.ukuu.org.uk> Content-Disposition: inline Sender: netdev-owner@vger.kernel.org List-ID: Am Freitag, 24. Juli 2009 16:19:41 schrieb Alan Cox: > On Fri, 24 Jul 2009 16:12:41 +0200 > > Oliver Neukum wrote: > > Am Freitag, 24. Juli 2009 14:48:05 schrieb Alan Cox: > > > > No, I was thinking of having two full devices, a data channel and a > > > > control channel for devices that really talk AT commands natively. > > > > > > If the hardware does it great, however for things like a 3G modem you > > > have the problem that the PPP is over the AT command channel which may > > > itself be multiplexed. And the muxing in question is *ugly* - sort of > > > HDLC and LAP-B done wrong. > > > > Well, yes, but we would really like a separate control channel, so we > > can query parameters like signal strength, while we do PPP over the data > > channel. > > Thats the notion of the AT mux stuff - you get multiple AT channels and > you can stuff PPP down one of them. It's still butt ugly. That is a problem. But is it so ugly that we'd forgo the added functionality rather than implement it in the kernel? If not, I maintain that we should not maintain several different control channel interfaces, like some devices use cdc-wdm, others a ttyUSB and the AT mux stuff shall use yet a different method. Regards Oliver