From patchwork Mon Feb 28 17:24:40 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 547200 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 681A6C433F5 for ; Mon, 28 Feb 2022 17:33:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237665AbiB1ReJ (ORCPT ); Mon, 28 Feb 2022 12:34:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42218 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238359AbiB1RdT (ORCPT ); Mon, 28 Feb 2022 12:33:19 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6E01E8F9B8; Mon, 28 Feb 2022 09:29:52 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 18D4361440; Mon, 28 Feb 2022 17:29:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2B719C340E7; Mon, 28 Feb 2022 17:29:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1646069383; bh=vEPAZ3lTc+fwgGKdNcNvLHd+Ln7uEJIIVY59/b1a6eI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GtlyPBEzNVapz7jF0tVTw0KcCgQSfHlXKYxDSXQTHCJerBIeWDA9TAOLMOTytWcpM /jh66RNGHLJvmMlhdJCn4deIlOTLRF0fPLepb3luKqnOILboeg5+oXxUssuWmK+ac8 StgYXtGkPORkPgZpFjtHBfDGY1j4qGgg3HWZbdqM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Daniel Starke Subject: [PATCH 4.19 34/34] tty: n_gsm: fix encoding of control signal octet bit DV Date: Mon, 28 Feb 2022 18:24:40 +0100 Message-Id: <20220228172211.396581571@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220228172207.090703467@linuxfoundation.org> References: <20220228172207.090703467@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: daniel.starke@siemens.com commit 737b0ef3be6b319d6c1fd64193d1603311969326 upstream. n_gsm is based on the 3GPP 07.010 and its newer version is the 3GPP 27.010. See https://portal.3gpp.org/desktopmodules/Specifications/SpecificationDetails.aspx?specificationId=1516 The changes from 07.010 to 27.010 are non-functional. Therefore, I refer to the newer 27.010 here. Chapter 5.4.6.3.7 describes the encoding of the control signal octet used by the MSC (modem status command). The same encoding is also used in convergence layer type 2 as described in chapter 5.5.2. Table 7 and 24 both require the DV (data valid) bit to be set 1 for outgoing control signal octets sent by the DTE (data terminal equipment), i.e. for the initiator side. Currently, the DV bit is only set if CD (carrier detect) is on, regardless of the side. This patch fixes this behavior by setting the DV bit on the initiator side unconditionally. Fixes: e1eaea46bb40 ("tty: n_gsm line discipline") Cc: stable@vger.kernel.org Signed-off-by: Daniel Starke Link: https://lore.kernel.org/r/20220218073123.2121-1-daniel.starke@siemens.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/n_gsm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -428,7 +428,7 @@ static u8 gsm_encode_modem(const struct modembits |= MDM_RTR; if (dlci->modem_tx & TIOCM_RI) modembits |= MDM_IC; - if (dlci->modem_tx & TIOCM_CD) + if (dlci->modem_tx & TIOCM_CD || dlci->gsm->initiator) modembits |= MDM_DV; return modembits; }