From nobody Thu Sep 4 03:26:07 2025 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 A1B9FC54EE9 for ; Tue, 13 Sep 2022 15:16:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234449AbiIMPQh (ORCPT ); Tue, 13 Sep 2022 11:16:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56616 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235838AbiIMPN7 (ORCPT ); Tue, 13 Sep 2022 11:13:59 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EF761786F8; Tue, 13 Sep 2022 07:33:31 -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 2EB15614D8; Tue, 13 Sep 2022 14:33:03 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2908AC433C1; Tue, 13 Sep 2022 14:33:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1663079582; bh=tFKe29vBsrtAsOOzBfGmnkFi9oNi877R8GhDW+yP4ow=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DBiXmeFvs9mWKBEUNxWdz5v8QlX0WkzXNdNveAHfuOxm2MosOERBlgT3whtLX9jMr Fa1K2mzP0D0D+zd+bUulAN1GuZDiKAtb6KHn1rHu/cAlN1hjM4TpejHoe2XWrF2V45 eiEpnZDFzOCb9XO5SryzUr6nXLN6rRHeQGxDCTIw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jonathan Woithe , Johan Hovold Subject: [PATCH 4.19 75/79] USB: serial: ch341: fix disabled rx timer on older devices Date: Tue, 13 Sep 2022 16:07:33 +0200 Message-Id: <20220913140352.508538258@linuxfoundation.org> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20220913140348.835121645@linuxfoundation.org> References: <20220913140348.835121645@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Johan Hovold commit 41ca302a697b64a3dab4676e01d0d11bb184737d upstream. At least one older CH341 appears to have the RX timer enable bit inverted so that setting it disables the RX timer and prevents the FIFO from emptying until it is full. Only set the RX timer enable bit for devices with version newer than 0x27 (even though this probably affects all pre-0x30 devices). 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 reconfigurat= ion") Cc: stable@vger.kernel.org # 4.10 Signed-off-by: Johan Hovold [ johan: backport to 5.4 ] Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman --- drivers/usb/serial/ch341.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) --- a/drivers/usb/serial/ch341.c +++ b/drivers/usb/serial/ch341.c @@ -176,8 +176,12 @@ static int ch341_set_baudrate_lcr(struct /* * CH341A buffers data until a full endpoint-size packet (32 bytes) * has been received unless bit 7 is set. + * + * At least one device with version 0x27 appears to have this bit + * inverted. */ - a |=3D BIT(7); + if (priv->version > 0x27) + a |=3D BIT(7); =20 r =3D ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x1312, a); if (r)