From patchwork Tue Jan 11 07:23:17 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "D. Starke" X-Patchwork-Id: 531737 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 576D2C433F5 for ; Tue, 11 Jan 2022 07:36:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235278AbiAKHgR (ORCPT ); Tue, 11 Jan 2022 02:36:17 -0500 Received: from thoth.sbs.de ([192.35.17.2]:37462 "EHLO thoth.sbs.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348539AbiAKHgR (ORCPT ); Tue, 11 Jan 2022 02:36:17 -0500 X-Greylist: delayed 735 seconds by postgrey-1.27 at vger.kernel.org; Tue, 11 Jan 2022 02:36:16 EST Received: from mail2.sbs.de (mail2.sbs.de [192.129.41.66]) by thoth.sbs.de (8.15.2/8.15.2) with ESMTPS id 20B7NmpG030985 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 11 Jan 2022 08:23:48 +0100 Received: from ubuntu.localdomain ([139.21.146.160]) by mail2.sbs.de (8.15.2/8.15.2) with ESMTP id 20B7Nl7a032292; Tue, 11 Jan 2022 08:23:47 +0100 From: Daniel Starke To: linux-serial@vger.kernel.org, gregkh@linuxfoundation.org, jirislaby@kernel.org Cc: linux-kernel@vger.kernel.org, Daniel Starke Subject: [PATCH 1/1] tty: n_gsm: Fix SW flow control encoding/handling Date: Mon, 10 Jan 2022 23:23:17 -0800 Message-Id: <20220111072317.2082-1-daniel.starke@siemens.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org According to 3GPP 27.010 chapter 5.2.7.3 DC1 and DC3 (SW flow control) are to be treated according to ISO/IEC 646. That means the MSB shall be ignored. This patch applies the needed changes to handle this correctly. Signed-off-by: Daniel Starke --- drivers/tty/n_gsm.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index 0b96b14bbfe1..9ee0643fc9e2 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -322,6 +322,7 @@ static int addr_cnt; #define GSM1_ESCAPE_BITS 0x20 #define XON 0x11 #define XOFF 0x13 +#define ASCII_MASK 0x7F static const struct tty_port_operations gsm_port_ops; @@ -521,7 +522,7 @@ static void gsm_print_packet(const char *hdr, int addr, int cr, * @output: output buffer * @len: length of input * - * Expand a buffer by bytestuffing it. The worst case size change + * Expand a buffer by byte stuffing it. The worst case size change * is doubling and the caller is responsible for handing out * suitable sized buffers. */ @@ -531,7 +532,8 @@ static int gsm_stuff_frame(const u8 *input, u8 *output, int len) int olen = 0; while (len--) { if (*input == GSM1_SOF || *input == GSM1_ESCAPE - || *input == XON || *input == XOFF) { + || (*input & ASCII_MASK) == XON + || (*input & ASCII_MASK) == XOFF) { *output++ = GSM1_ESCAPE; *output++ = *input++ ^ GSM1_ESCAPE_BITS; olen++;