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 0DE41ECAAA1 for ; Tue, 6 Sep 2022 14:20:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241528AbiIFOUf (ORCPT ); Tue, 6 Sep 2022 10:20:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37890 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242074AbiIFOTa (ORCPT ); Tue, 6 Sep 2022 10:19:30 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9BA578A7EC; Tue, 6 Sep 2022 06:50:42 -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 ams.source.kernel.org (Postfix) with ESMTPS id 5D743B81633; Tue, 6 Sep 2022 13:49:16 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 08E86C433C1; Tue, 6 Sep 2022 13:49:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1662472155; bh=6DAkq7iQ7tCJ0q+KIEGziZiVYdN2cdYJzvu00FR63+U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=P7l4tHfYjRRsaGsGKdGNTEUVgkqsBJVMsH8qe6Fv+SjWp8+mkH8k+Nmo24nyK0I5Q NxEGEbprW/hJ1q2Gzhos9p6Tw6VLVgtdGik8TLh34mapDljG/3ikPSCe2hOMCFQQTu xa0RigwIdZwM6c2665Dmo09QYZ7INkRPhtDpIM2yXLvYsl2BdviN30K8thX6OaiBRy qaGfKFpbKqq5WfS3e5Xw7bVXEyosKsLLsH8fPw/XUvfCaxNT/5YI3nP6UwtXtF1hyZ 5Y5HB456uP1+fKoZRg9Vt9CXpHK5YnjpKGCyELUgRDO7WcooUP6/vmZchC907vTjzw mDR+FLnMH2Flg== Received: from johan by xi.lan with local (Exim 4.94.2) (envelope-from ) id 1oVYx5-00050V-Ij; Tue, 06 Sep 2022 15:49:19 +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-4.19 3/4] USB: serial: ch341: fix lost character on LCR updates Date: Tue, 6 Sep 2022 15:49:14 +0200 Message-Id: <20220906134915.19225-4-johan@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220906134915.19225-1-johan@kernel.org> References: <20220906134915.19225-1-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 4.19 ] 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 f789b60ed8c1..58b5fd95b29f 100644 --- a/drivers/usb/serial/ch341.c +++ b/drivers/usb/serial/ch341.c @@ -96,6 +96,8 @@ struct ch341_private { u8 mcr; u8 msr; u8 lcr; + + u8 version; }; static void ch341_set_termios(struct tty_struct *tty, @@ -181,6 +183,9 @@ 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; @@ -232,7 +237,9 @@ 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