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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4C581C54EE9 for ; Tue, 13 Sep 2022 16:24:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230314AbiIMQYR (ORCPT ); Tue, 13 Sep 2022 12:24:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47382 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230350AbiIMQXl (ORCPT ); Tue, 13 Sep 2022 12:23:41 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3FE82A98FD; Tue, 13 Sep 2022 08:18:24 -0700 (PDT) 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 072C8614CE; Tue, 13 Sep 2022 14:36:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1F886C433D6; Tue, 13 Sep 2022 14:36:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1663079767; bh=/FD+XJlkiYnUlmeTNebsc0OZTkHSly0huwW07NOq6uY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EhD5onltNePqUP5a0vuNlXC9Zhc1iIR2UjxCjzIKll3cP1ELxFAz7dGb8luV+Ss92 AALB+j/KgVzUqyCti7fUyq4nGyXyl5ii5yeBq//dUYPXfFvKVT2IxLM206Hn/O9KwL 91S5iArkBe1e6uCLV638pzFdS6qCIRGQTSJp7Xr8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jonathan Woithe , Johan Hovold Subject: [PATCH 4.14 58/61] USB: serial: ch341: fix lost character on LCR updates Date: Tue, 13 Sep 2022 16:08:00 +0200 Message-Id: <20220913140349.360305890@linuxfoundation.org> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20220913140346.422813036@linuxfoundation.org> References: <20220913140346.422813036@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Johan Hovold commit 8e83622ae7ca481c76c8fd9579877f6abae64ca2 upstream. Disable LCR updates for pre-0x30 devices which use a different (unknown) protocol for line control and where the current register write causes the next received character to be lost. Note that updating LCR using the INIT command has no effect on these devices either. Reported-by: Jonathan Woithe Tested-by: Jonathan Woithe Link: https://lore.kernel.org/r/Ys1iPTfiZRWj2gXs@marvin.atrad.com.au Fixes: 4e46c410e050 ("USB: serial: ch341: reinitialize chip on reconfiguration") Fixes: 55fa15b5987d ("USB: serial: ch341: fix baud rate and line-control handling") Cc: stable@vger.kernel.org # 4.10 Signed-off-by: Johan Hovold [ johan: adjust context to 4.19 ] Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman --- drivers/usb/serial/ch341.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) --- a/drivers/usb/serial/ch341.c +++ b/drivers/usb/serial/ch341.c @@ -99,6 +99,8 @@ struct ch341_private { u8 mcr; u8 msr; u8 lcr; + + u8 version; }; static void ch341_set_termios(struct tty_struct *tty, @@ -184,6 +186,9 @@ static int ch341_set_baudrate_lcr(struct if (r) return r; + if (priv->version < 0x30) + return 0; + r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x2518, lcr); if (r) return r; @@ -235,7 +240,9 @@ static int ch341_configure(struct usb_de r = ch341_control_in(dev, CH341_REQ_READ_VERSION, 0, 0, buffer, size); if (r < 0) goto out; - dev_dbg(&dev->dev, "Chip version: 0x%02x\n", buffer[0]); + + priv->version = buffer[0]; + dev_dbg(&dev->dev, "Chip version: 0x%02x\n", priv->version); r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT, 0, 0); if (r < 0)