Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756838AbaAHPn6 (ORCPT ); Wed, 8 Jan 2014 10:43:58 -0500 Received: from atlantis.wh2.tu-dresden.de ([141.30.228.39]:56981 "EHLO atlantis.wh2.tu-dresden.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755301AbaAHPnz (ORCPT ); Wed, 8 Jan 2014 10:43:55 -0500 From: Lars Poeschel To: poeschel@lemonage.de, rob@landley.net, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, alan@linux.intel.com Subject: [PATCH] n_gsm/documentation: Add some words about DCD signal Date: Wed, 8 Jan 2014 16:42:55 +0100 Message-Id: <1389195775-22959-1-git-send-email-larsi@wh2.tu-dresden.de> X-Mailer: git-send-email 1.8.5.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Lars Poeschel Add some words about modem control lines, DCD signal and that an open may block to the n_gsm documentation. Signed-off-by: Lars Poeschel --- Documentation/serial/n_gsm.txt | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/Documentation/serial/n_gsm.txt b/Documentation/serial/n_gsm.txt index a5d9112..089b934 100644 --- a/Documentation/serial/n_gsm.txt +++ b/Documentation/serial/n_gsm.txt @@ -74,6 +74,12 @@ done for example, it's possible : - and to use gnokii to send / receive SMS on ttygsm1 - to use ppp to establish a datalink on ttygsm2 +- If you want to use a virtual muxed channel in your own programs, be aware + that it respects the modem control lines. If you open the virtual port it + will block, if it is not connected to a carrier (DCD signal missing). You + could open the virtual port with O_NDELAY flag and do normal AT commands + to the modem without a carrier. You can change to blocking mode later if + you need this with fcntl F_SETFL/F_GETFL. 6- first close all virtual ports before closing the physical port. -- 1.8.5.2 -- 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/