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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 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 AFF23C433E0 for ; Mon, 25 May 2020 15:03:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 93E9B2078B for ; Mon, 25 May 2020 15:03:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390911AbgEYPDA (ORCPT ); Mon, 25 May 2020 11:03:00 -0400 Received: from mx2.suse.de ([195.135.220.15]:48240 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725809AbgEYPDA (ORCPT ); Mon, 25 May 2020 11:03:00 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 2C455AC9F; Mon, 25 May 2020 15:03:01 +0000 (UTC) Message-ID: <1590418977.2838.16.camel@suse.com> Subject: Re: ttyACM: disabled by hub (EMI?), re-enabling... Causes garbage chars & disconnect From: Oliver Neukum To: Joakim Tjernlund , "linux-usb@vger.kernel.org" Date: Mon, 25 May 2020 17:02:57 +0200 In-Reply-To: <6a4fe396ab5ae6cda548e904c57bc823103999d7.camel@infinera.com> References: <6a4fe396ab5ae6cda548e904c57bc823103999d7.camel@infinera.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.26.6 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org Am Montag, den 25.05.2020, 14:46 +0000 schrieb Joakim Tjernlund: > This (EMI?) disconnect causes 2 things. > 1) I loose the TTY temporarily and have to reconnect. Unfortunately I see no way to reestablish contact transparantly on the level of the driver. > 2) After reconnect there are garbage chars on the gadget side, such as: > h�^@^@� ^@^@� ^@ This looks like MM is acting up in user space. > or > X���)H��4Ğ^��� > which causes confusion on for the tty/bash on the gadget. > > The disconnect is mostly just annoying but the garbage chars are a major pain, one cannot trust > that cmds are understod. Is there a bug in ttyACM driver causing these? Hi, thanks for the bug report. The most likely cause of your problem is ModemManager probing the new device. It has a blacklist. HTH Oliver