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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 CDE87C43381 for ; Tue, 19 Mar 2019 14:30:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A70B82085A for ; Tue, 19 Mar 2019 14:30:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727532AbfCSOa2 (ORCPT ); Tue, 19 Mar 2019 10:30:28 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57766 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726466AbfCSOa2 (ORCPT ); Tue, 19 Mar 2019 10:30:28 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id CC0B0307EA87; Tue, 19 Mar 2019 14:30:27 +0000 (UTC) Received: from ovpn-112-62.rdu2.redhat.com (ovpn-112-62.rdu2.redhat.com [10.10.112.62]) by smtp.corp.redhat.com (Postfix) with ESMTP id 44E942854C; Tue, 19 Mar 2019 14:30:26 +0000 (UTC) Message-ID: <6c89938b00ad289e1802f675bd00e288b1458d73.camel@redhat.com> Subject: Re: [PATCH] USB: serial: option: set driver_info for SIM5218 and compatibles From: Dan Williams To: Johan Hovold , =?ISO-8859-1?Q?M=E5ns_Rullg=E5rd?= Cc: =?ISO-8859-1?Q?Bj=F8rn?= Mork , Greg Kroah-Hartman , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Date: Tue, 19 Mar 2019 09:30:25 -0500 In-Reply-To: <20190319124358.GK6124@localhost> References: <20190226170710.12709-1-mans@mansr.com> <20190227083342.GJ4747@localhost> <20190227131315.GO4747@localhost> <20190319102840.GI6124@localhost> <20190319110819.GB3178@localhost> <20190319122719.GC3178@localhost> <20190319124358.GK6124@localhost> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.30.5 (3.30.5-1.fc29) MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.44]); Tue, 19 Mar 2019 14:30:28 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2019-03-19 at 13:43 +0100, Johan Hovold wrote: > On Tue, Mar 19, 2019 at 01:27:19PM +0100, Johan Hovold wrote: > > On Tue, Mar 19, 2019 at 12:25:53PM +0000, Måns Rullgård wrote: > > > Johan Hovold writes: > > > > > > > On Tue, Mar 19, 2019 at 10:54:00AM +0000, Måns Rullgård wrote: > > > > > Johan Hovold writes: > > > > > > > Regardless, setting the NCTRL flag should be harmless. > > > > > > > > > > > > Well, there are devices that depend on getting these > > > > > > requests, at least > > > > > > for the QMI interface. But we can always revert if anyone > > > > > > complains. > > > > > > > > > > The QMI interface doesn't even pretend to be a uart. The > > > > > other ones do, > > > > > but there isn't actually any real uart behind them. For > > > > > instance, it > > > > > doesn't matter what baud rate one sets. > > > > > > > > Sure, but some devices still require "DTR" to be set for the > > > > QMI > > > > interface, so there not being any real uart is no guarantee > > > > that there > > > > is no firmware that expects these calls. > > > > > > Now I'm thoroughly confused. The QMI interface has a completely > > > separate driver that creates a network device (if I'm reading the > > > code > > > correctly). > > > > I was just giving an example of firmware sometimes doing unexpected > > things. > > See 93725149794d ("net: qmi_wwan: MDM9x30 specific power management") > for some background. TLDR; some firmware uses the DTR signal as an indicator to come out of low-power mode. Without doing so you cannot talk to the modem over any of it's ports, QMI, net, or serial. Dan