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 X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 82A18C433E0 for ; Tue, 9 Jun 2020 17:58:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 625D120734 for ; Tue, 9 Jun 2020 17:58:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591725481; bh=cVDViZWwgHNsufUmT2I+Hp2X1qg/QoZVvKpHAG/7+i8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=HN6sMZ06zrPXkI6/I27vwDA/1h7cOoOaVLDXrkaSm9OpxCtgKEkII4qPb25+ViNtH ElNwkiYVAMzJgc4h4qRIpg+te1id7LpFWa8tTg7FbtcQnxtKItib7TEMTygXXayfKV l5OxkDIKDxwiUc19G6cJ7gNaXgIy5drL5lB4AHsE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731771AbgFIRzj (ORCPT ); Tue, 9 Jun 2020 13:55:39 -0400 Received: from mail.kernel.org ([198.145.29.99]:45128 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731621AbgFIRxv (ORCPT ); Tue, 9 Jun 2020 13:53:51 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id ED8CE20774; Tue, 9 Jun 2020 17:53:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591725230; bh=cVDViZWwgHNsufUmT2I+Hp2X1qg/QoZVvKpHAG/7+i8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hAPwyxAOw1F+WwuWJE6MeFPzxtMg2tT0OqhMoH26skMcDrhCCjoy/T80R99pLkKZl 3kTf9s7RRLfShGRN9SmHyhBXD1bLhzN9hftq6cEmzzNrNWsH/QR2aIGwliZPOeyIfg l9l9PsGqMr/lOABNESYK858+CPUoNkimHn+GITE0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Michael Hanselmann , Johan Hovold Subject: [PATCH 5.6 22/41] USB: serial: ch341: fix lockup of devices with limited prescaler Date: Tue, 9 Jun 2020 19:45:24 +0200 Message-Id: <20200609174114.240869918@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200609174112.129412236@linuxfoundation.org> References: <20200609174112.129412236@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Johan Hovold commit c432df155919582a3cefa35a8f86256c830fa9a4 upstream. Michael Hanselmann reports that [a] subset of all CH341 devices stop responding to bulk transfers, usually after the third byte, when the highest prescaler bit (0b100) is set. There is one exception, namely a prescaler of exactly 0b111 (fact=1, ps=3). Fix this by forcing a lower base clock (fact = 0) whenever needed. This specifically makes the standard rates 110, 134 and 200 bps work again with these devices. Fixes: 35714565089e ("USB: serial: ch341: reimplement line-speed handling") Cc: stable # 5.5 Reported-by: Michael Hanselmann Link: https://lore.kernel.org/r/20200514141743.GE25962@localhost Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman --- drivers/usb/serial/ch341.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) --- a/drivers/usb/serial/ch341.c +++ b/drivers/usb/serial/ch341.c @@ -73,6 +73,8 @@ #define CH341_LCR_CS6 0x01 #define CH341_LCR_CS5 0x00 +#define CH341_QUIRK_LIMITED_PRESCALER BIT(0) + static const struct usb_device_id id_table[] = { { USB_DEVICE(0x4348, 0x5523) }, { USB_DEVICE(0x1a86, 0x7523) }, @@ -160,9 +162,11 @@ static const speed_t ch341_min_rates[] = * 2 <= div <= 256 if fact = 0, or * 9 <= div <= 256 if fact = 1 */ -static int ch341_get_divisor(speed_t speed) +static int ch341_get_divisor(struct ch341_private *priv) { unsigned int fact, div, clk_div; + speed_t speed = priv->baud_rate; + bool force_fact0 = false; int ps; /* @@ -188,8 +192,12 @@ static int ch341_get_divisor(speed_t spe clk_div = CH341_CLK_DIV(ps, fact); div = CH341_CLKRATE / (clk_div * speed); + /* Some devices require a lower base clock if ps < 3. */ + if (ps < 3 && (priv->quirks & CH341_QUIRK_LIMITED_PRESCALER)) + force_fact0 = true; + /* Halve base clock (fact = 0) if required. */ - if (div < 9 || div > 255) { + if (div < 9 || div > 255 || force_fact0) { div /= 2; clk_div *= 2; fact = 0; @@ -228,7 +236,7 @@ static int ch341_set_baudrate_lcr(struct if (!priv->baud_rate) return -EINVAL; - val = ch341_get_divisor(priv->baud_rate); + val = ch341_get_divisor(priv); if (val < 0) return -EINVAL; @@ -333,6 +341,7 @@ static int ch341_detect_quirks(struct us CH341_REG_BREAK, 0, buffer, size, DEFAULT_TIMEOUT); if (r == -EPIPE) { dev_dbg(&port->dev, "break control not supported\n"); + quirks = CH341_QUIRK_LIMITED_PRESCALER; r = 0; goto out; }