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 53C89C6FA83 for ; Tue, 6 Sep 2022 13:39:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229631AbiIFNjo (ORCPT ); Tue, 6 Sep 2022 09:39:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38386 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240803AbiIFNht (ORCPT ); Tue, 6 Sep 2022 09:37:49 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5A1931EEE7; Tue, 6 Sep 2022 06:34:48 -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 sin.source.kernel.org (Postfix) with ESMTPS id 0C8B2CE1771; Tue, 6 Sep 2022 13:34:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D33BBC433D6; Tue, 6 Sep 2022 13:34:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1662471274; bh=LzwaatPM3hNldsGc6C17lYweTPagmZOQHDFn+HmOCNs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NDf9myQNXbEbw0Pi7xAGf165ad6z5MJKc6tCoMYQruoWPIYmqfQATf1ViFysZ/8Qh x2DFbQil/8kw9Q4i8ObY4MPH30EIQV7xEp42pYqzkkefywK3rad6/IHfEMGebc3E5Z 4FMDG2lKYT3Uy0SU1RdPrTTmZDA8Wi1ldwIQpLLsOlGsYGpyngKH4xxTjs1UPhrnsJ mJTM/GOkoO1FfY5E5sjcRFeHt7cKBmQawt0lbjZ082vT/Y4w0c6LKD3HJyhpjq73ne S4KBa/hoaG8oe64rG4v5IpxJRGPsthk5rBTNWX4vy2YQDi+fmOPtLjcNnHEq1AgotL YwOP8BQvvJdBA== Received: from johan by xi.lan with local (Exim 4.94.2) (envelope-from ) id 1oVYit-0006sz-7j; Tue, 06 Sep 2022 15:34:39 +0200 From: Johan Hovold To: Greg Kroah-Hartman Cc: stable@vger.kernel.org, linux-kernel@vger.kernel.org, Johan Hovold , Jonathan Woithe Subject: [PATCH stable-5.4 2/3] USB: serial: ch341: fix lost character on LCR updates Date: Tue, 6 Sep 2022 15:34:34 +0200 Message-Id: <20220906133435.26452-3-johan@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220906133435.26452-1-johan@kernel.org> References: <20220906133435.26452-1-johan@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 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 5.4 ] Signed-off-by: Johan Hovold --- drivers/usb/serial/ch341.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c index f06a09e59d8b..be44d6c28df6 100644 --- a/drivers/usb/serial/ch341.c +++ b/drivers/usb/serial/ch341.c @@ -96,7 +96,9 @@ struct ch341_private { u8 mcr; u8 msr; u8 lcr; + unsigned long quirks; + u8 version; }; static void ch341_set_termios(struct tty_struct *tty, @@ -182,6 +184,9 @@ static int ch341_set_baudrate_lcr(struct usb_device *dev, 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; @@ -233,7 +238,9 @@ static int ch341_configure(struct usb_device *dev, struct ch341_private *priv) 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) -- 2.35.1