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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 8592EC4CEC9 for ; Fri, 13 Sep 2019 20:09:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 53C2C20678 for ; Fri, 13 Sep 2019 20:09:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388926AbfIMUJR convert rfc822-to-8bit (ORCPT ); Fri, 13 Sep 2019 16:09:17 -0400 Received: from shards.monkeyblade.net ([23.128.96.9]:48752 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388418AbfIMUJR (ORCPT ); Fri, 13 Sep 2019 16:09:17 -0400 Received: from localhost (93-63-141-166.ip28.fastwebnet.it [93.63.141.166]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id B8E4D1539B194; Fri, 13 Sep 2019 13:09:15 -0700 (PDT) Date: Fri, 13 Sep 2019 21:09:14 +0100 (WEST) Message-Id: <20190913.210914.459044600119292225.davem@davemloft.net> To: bjorn@mork.no Cc: netdev@vger.kernel.org, oliver@neukum.org, linux-usb@vger.kernel.org, larsm17@gmail.com Subject: Re: [PATCH net,stable] cdc_ether: fix rndis support for Mediatek based smartphones From: David Miller In-Reply-To: <20190912084200.6359-1-bjorn@mork.no> References: <20190912084200.6359-1-bjorn@mork.no> X-Mailer: Mew version 6.8 on Emacs 26.2 Mime-Version: 1.0 Content-Type: Text/Plain; charset=iso-8859-1 Content-Transfer-Encoding: 8BIT X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Fri, 13 Sep 2019 13:09:16 -0700 (PDT) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Bjørn Mork Date: Thu, 12 Sep 2019 10:42:00 +0200 > A Mediatek based smartphone owner reports problems with USB > tethering in Linux. The verbose USB listing shows a rndis_host > interface pair (e0/01/03 + 10/00/00), but the driver fails to > bind with > > [ 355.960428] usb 1-4: bad CDC descriptors > > The problem is a failsafe test intended to filter out ACM serial > functions using the same 02/02/ff class/subclass/protocol as RNDIS. > The serial functions are recognized by their non-zero bmCapabilities. > > No RNDIS function with non-zero bmCapabilities were known at the time > this failsafe was added. But it turns out that some Wireless class > RNDIS functions are using the bmCapabilities field. These functions > are uniquely identified as RNDIS by their class/subclass/protocol, so > the failing test can safely be disabled. The same applies to the two > types of Misc class RNDIS functions. > > Applying the failsafe to Communication class functions only retains > the original functionality, and fixes the problem for the Mediatek based > smartphone. > > Tow examples of CDC functional descriptors with non-zero bmCapabilities > from Wireless class RNDIS functions are: ... > The Mediatek example is believed to apply to most smartphones with > Mediatek firmware. The ZTE example is most likely also part of a larger > family of devices/firmwares. > > Suggested-by: Lars Melin > Signed-off-by: Bjørn Mork Applied and queued up for -stable, thanks.