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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 C37BCC4CECD for ; Mon, 16 Sep 2019 13:41:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A2B1E216C8 for ; Mon, 16 Sep 2019 13:41:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387660AbfIPNlx (ORCPT ); Mon, 16 Sep 2019 09:41:53 -0400 Received: from mx1.emlix.com ([188.40.240.192]:49096 "EHLO mx1.emlix.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733054AbfIPNlw (ORCPT ); Mon, 16 Sep 2019 09:41:52 -0400 Received: from mailer.emlix.com (unknown [81.20.119.6]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.emlix.com (Postfix) with ESMTPS id 186535FAD2; Mon, 16 Sep 2019 15:41:50 +0200 (CEST) Subject: Re: [PATCH 0/4] Fix UART DMA freezes for iMX6 To: Robin Gong , "linux-kernel@vger.kernel.org" Cc: "vkoul@kernel.org" , "dan.j.williams@intel.com" , "shawnguo@kernel.org" , "s.hauer@pengutronix.de" , "kernel@pengutronix.de" , "festevam@gmail.com" , dl-linux-imx , "gregkh@linuxfoundation.org" , "jslaby@suse.com" , "dmaengine@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-serial@vger.kernel.org" References: <20190911144943.21554-1-philipp.puschmann@emlix.com> From: Philipp Puschmann Openpgp: preference=signencrypt Message-ID: <29d03762-866a-4fdc-eddb-e24f6e631412@emlix.com> Date: Mon, 16 Sep 2019 15:41:49 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: de-DE Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am 16.09.19 um 10:02 schrieb Robin Gong: > On 2019/9/11 Philipp Puschmann wrote: >> For some years and since many kernel versions there are reports that RX >> UART DMA channel stops working at one point. So far the usual workaround >> was to disable RX DMA. This patches try to fix the underlying problem. >> >> When a running sdma script does not find any usable destination buffer to put >> its data into it just leads to stopping the channel being scheduled again. As >> solution we we manually retrigger the sdma script for this channel and by this >> dissolve the freeze. >> >> While this seems to work fine so far a further patch in this series increases the >> number of RX DMA periods for UART to reduce use cases running into such a >> situation. >> >> This patch series was tested with the current kernel and backported to kernel >> 4.15 with a special use case using a WL1837MOD via UART and provoking the > Hi Philipp, Could your Bluetooth issue be reproduce on latest linux-next? Or did > your kernel which can be reproduced include the below patch? > > commit d1a792f3b4072bfac4150bb62aa34917b77fdb6d > Author: Russell King - ARM Linux > Date: Wed Jun 25 13:00:33 2014 +0100 > Hi Robin, yes i have reproduced the Bluetooth issue with my test case with kernel 4.15 and the newest 5.3.0-rc8-next-20190915. My test-case includes several custom-boards communicating via Bluetooth with each other. I see the error within seconds to few minutes. > Update imx-sdma cyclic handling to report residue >> hanging of UART RX DMA within seconds after starting a test application. >> It resulted in well known >> "Bluetooth: hci0: command 0x0408 tx timeout" >> errors and complete stop of UART data reception. Our Bluetooth traffic >> consists of many independent small packets, mostly only a few bytes, causing >> high usage of periods. >> >> >> Philipp Puschmann (4): >> dmaengine: imx-sdma: fix buffer ownership >> dmaengine: imx-sdma: fix dma freezes >> serial: imx: adapt rx buffer and dma periods >> dmaengine: imx-sdma: drop redundant variable >> >> drivers/dma/imx-sdma.c | 32 ++++++++++++++++++++++---------- >> drivers/tty/serial/imx.c | 5 ++--- >> 2 files changed, 24 insertions(+), 13 deletions(-) >> >> -- >> 2.23.0 > -- Philipp Puschmann, emlix GmbH, http://www.emlix.com Fon +49 551 30664-0, Fax +49 551 30664-11 Gothaer Platz 3, 37083 Göttingen, Germany Sitz der Gesellschaft: Göttingen, Amtsgericht Goettingen HR B 3160 Geschaeftsführung: Heike Jordan, Dr. Uwe Kracke Ust-IdNr.: DE 205 198 055 emlix - smart embedded open source