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=-3.8 required=3.0 tests=BAYES_00, 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 39D8DC433E0 for ; Sun, 21 Feb 2021 10:59:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E7E6164E24 for ; Sun, 21 Feb 2021 10:59:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229897AbhBUK7L convert rfc822-to-8bit (ORCPT ); Sun, 21 Feb 2021 05:59:11 -0500 Received: from mailer.bingner.com ([64.62.210.4]:29170 "EHLO mail.bingner.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229540AbhBUK7H (ORCPT ); Sun, 21 Feb 2021 05:59:07 -0500 X-Greylist: delayed 941 seconds by postgrey-1.27 at vger.kernel.org; Sun, 21 Feb 2021 05:59:07 EST Received: from EX02.ds.sbdhi.com (2001:470:3c:1::22) by EX01.ds.sbdhi.com (2001:470:3c:1::21) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2044.4; Sun, 21 Feb 2021 00:42:44 -1000 Received: from EX02.ds.sbdhi.com ([fe80::8911:a681:797:3bb6]) by EX02.ds.sbdhi.com ([fe80::8911:a681:797:3bb6%2]) with mapi id 15.01.2044.004; Sun, 21 Feb 2021 00:42:44 -1000 From: Sam Bingner To: "linux-usb@vger.kernel.org" CC: "David S. Miller" , Martin Habets , Luc Van Oostenryck , Shannon Nelson , "Michael S. Tsirkin" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Matti Vuorela , Jakub Kicinski , "Yves-Alexis Perez" Subject: Re: [PATCH] usbnet: ipheth: fix connectivity with iOS 14 Thread-Topic: Re: [PATCH] usbnet: ipheth: fix connectivity with iOS 14 Thread-Index: AdcIPCziP88UnOb2Try4p4IFfkZ3BQ== Date: Sun, 21 Feb 2021 10:42:44 +0000 Message-ID: <370902e520c44890a44cb5dd0cb1595f@bingner.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [98.155.121.8] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There seems to be a problem with this patch: Whenever the iPhone sends a packet to the tethered device that is 1500 bytes long, it gets the error "ipheth 1-1:4.2: ipheth_rcvbulk_callback: urb status: -79" on the connected device and stops passing traffic. I am able to bring it back up by shutting and unshutting the interface, but the same thing happens very quickly. I noticed that this patch dropped the max USB packet size from 1516 to 1514 bytes, so I decided to try lowering the MTU to 1498; this made the connection reliable and no more errors occurred. It appears to me that the iPhone is still sending out 1516 bytes over USB for a 1500 byte packet and this patch makes USB abort when that happens? I could duplicate reliably by sending a ping from the iphone (ping -s 1472) to the connected device, or vice versa as the reply would then break it. I apologize if this reply doesn't end up where it should - I tried to reply to the last message in this thread but I wasn't actually *on* the thread so I had to just build it as much as possible myself. Sam