From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F2EE0C433E0 for ; Sun, 17 Jan 2021 17:29:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B79A32222F for ; Sun, 17 Jan 2021 17:29:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729907AbhAQR2A (ORCPT ); Sun, 17 Jan 2021 12:28:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38078 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728455AbhAQR15 (ORCPT ); Sun, 17 Jan 2021 12:27:57 -0500 Received: from canardo.mork.no (canardo.mork.no [IPv6:2001:4641::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7A34CC061573 for ; Sun, 17 Jan 2021 09:27:16 -0800 (PST) Received: from miraculix.mork.no (fwa136.mork.no [192.168.9.136]) (authenticated bits=0) by canardo.mork.no (8.15.2/8.15.2) with ESMTPSA id 10HHQt5j003973 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Sun, 17 Jan 2021 18:26:55 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mork.no; s=b; t=1610904416; bh=i47PqHy/XxOXMLZAW0NVDTePUMLKmi1DFXvfHx3nEJw=; h=From:To:Cc:Subject:References:Date:Message-ID:From; b=hCfQDsTjTh9vaPO6u7W3dOPTpWs5uyXaigI8ZrAkZrN6Q590Mt7oxfsZJBv7yLkNq bzASp1mDUJpj7oL34VqgofCFh7m8uOX5Z/ptyiSTSYdaSh+X6RLF0MzgqjqRwdP5+N l/Z9JNPDO1Zk6daq6A/Sxjp30cZ9SBgpzz3uNVs4= Received: from bjorn by miraculix.mork.no with local (Exim 4.94) (envelope-from ) id 1l1BpG-002NpQ-MU; Sun, 17 Jan 2021 18:26:54 +0100 From: =?utf-8?Q?Bj=C3=B8rn_Mork?= To: Andrew Lunn Cc: M Chetan Kumar , netdev@vger.kernel.org, linux-wireless@vger.kernel.org, johannes@sipsolutions.net, krishna.c.sudi@intel.com Subject: Re: [PATCH 17/18] net: iosm: readme file Organization: m References: <20210107170523.26531-1-m.chetan.kumar@intel.com> <20210107170523.26531-18-m.chetan.kumar@intel.com> Date: Sun, 17 Jan 2021 18:26:54 +0100 In-Reply-To: (Andrew Lunn's message of "Thu, 7 Jan 2021 23:23:58 +0100") Message-ID: <87turftqxt.fsf@miraculix.mork.no> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Virus-Scanned: clamav-milter 0.102.4 at canardo X-Virus-Status: Clean Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Sorry about being much too late into this discussion. I'm not having the bandwidth to read netdev anymore, and just stumbled across this now. Andrew Lunn writes: > So, this is what all the Ethernet nonsense is all about. You have a > session ID you need to somehow represent to user space. And you > decided to use VLANs. But to use VLANs, you need an Ethernet > header. So you added a bogus Ethernet header. Actually, the original reasoning was the other way around. The bogus ethernet header was added because I had seen the 3G modem vendors do that for a few years already, in the modem firmware. And I didn't think enough about it to realize that it was a really bad idea, or even that it was something I could change. Or should change. I cannot blame the MBIM sesison to VLAN mapping idea on anyone else. As far as I can remember, that was just something that popped up in my head while working on the cdc_mbim driver. But it came as a consequence of already having the bogus ethernet header. And I didn't really understand that I could define a new wwan subsystem with new device types. I thought I had to use whatever was there already. I was young and stupid. Now I'm not that young anymore ;-) Never ever imagined that this would be replicated in another driver, though. That doesn't really make much sense. We have learned by now, haven't we? This subject has been discussed a few times in the past, and Johannes summary is my understanding as well: "I don't think anyone likes that" The DSS mapping sucks even more that the IPS mapping, BTW. I don't think there are any real users? Not that I know of, at least. DSS is much better implmeneted as some per-session character device, as requested by numerous people for years. Sorry for not listening. Looks like it is too late now. > Is any of this VLAN stuff required by MBIM? No. It's my fault and mine alone. > I suggest you throw away the pretence this is an Ethernet device. It > is not. I completely agree. I wish I had gone for simple raw-ip devices both in the qmi_wwan and cdc_mbim. But qmi_wwan got them later, so there is already support for such things in wwan userspace. Bj=C3=B8rn