Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756622AbaAHN0j (ORCPT ); Wed, 8 Jan 2014 08:26:39 -0500 Received: from [85.220.129.32] ([85.220.129.32]:45504 "EHLO smtp1-3.goneo.de" rhost-flags-FAIL-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751224AbaAHN0h (ORCPT ); Wed, 8 Jan 2014 08:26:37 -0500 X-Spam-Flag: NO X-Spam-Score: -2.78 From: Lars Poeschel To: Alan Cox Cc: Greg KH , jslaby@suse.cz, linux-kernel@vger.kernel.org, xiaojin , Ken Mills , Dirkjan Bussink Subject: Re: [RFC DO NOT MERGE] tty: n_gsm: support buggy modem Date: Wed, 08 Jan 2014 14:26:03 +0100 Message-ID: <1599574.bGW69LnCZ1@lem-wkst-02> User-Agent: KMail/4.11.3 (Linux/3.11-2-amd64; KDE/4.11.3; x86_64; ; ) In-Reply-To: <1389113497.2735.142.camel@acox1-desk.ger.corp.intel.com> References: <4386658.RncifLMAGy@lem-wkst-02> <20140107142050.GB32491@kroah.com> <1389113497.2735.142.camel@acox1-desk.ger.corp.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am Dienstag, 7. Januar 2014, 16:51:37 schrieb Alan Cox: > > > modem status command, but this DV bit is not set. With this patch the > > > modem > > > and the whole mux is working fine. Another way makeing all this work is > > > setting the carrier_raised function to NULL. The tty code assumes that > > > everything is alright then. > > Which means your modem has decided it doesn't yet have a carrier. Do you > get a carrier after ATD completes with a CONNECTED message ? > > (you can open with O_NDELAY to avoid blocking on the open) Oh! Thank you! This does indeed bring up the channel. After opening nonblocking and writing ATD *99***1# to a muxed channel the modem sends a modem status command message with DV bit set. This does in fact mean, I can only use the mux in nonblocking mode. Does this make sense ? Why can't I use a muxed channel with blocking IO ? I could do AT commands over the mux channel and the DV bit is not set (and thus TIOCM_CD is not set) and the modem (and the mux line discipline) is fine with it. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/