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=-4.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 7FA4DC49ED6 for ; Wed, 11 Sep 2019 14:50:59 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 5317D20644 for ; Wed, 11 Sep 2019 14:50:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="qlgGQi3I" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5317D20644 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=emlix.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-Id:Date:Subject:To :From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=F9DYROJ1NDR73G8OEYAyFC5viwxbC4DvAHUaeZGor4o=; b=qlgGQi3IiHHgI0 pO8gnLTJVBB3/+YRDIBA8BGkx1+zMKyOfhT80fvhoC7ral1uPwxRznVBT5ryyJAOyWSQ8bTQDT0F5 Urz9pJnuTNB6lKeOKtasLSEfeaWAdjUVPMJ8dpAGcAidItA1jKITW92RfcO/p3jy5M2eo9MMGRt6s ONZyENU19s0mKmAYKe0Lc6dgYOaxkzivl4WXLDRNOgiIONh8w6MtijcmTVOUaeBUdcOcCDm302CZ6 zAp8SfxU5yHLClYCb26pCH5OKMHQGfam8BYbswSHkONIFSjg8kLL3L7pPQeRhk6WEGNA8ypCxpdzu RhXx6teGeIuaH7nNjpMA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.2 #3 (Red Hat Linux)) id 1i83xO-0007Fy-At; Wed, 11 Sep 2019 14:50:54 +0000 Received: from mx1.emlix.com ([188.40.240.192]) by bombadil.infradead.org with esmtps (Exim 4.92.2 #3 (Red Hat Linux)) id 1i83wa-0005QX-Qk for linux-arm-kernel@lists.infradead.org; Wed, 11 Sep 2019 14:50:08 +0000 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 A80495FBAB; Wed, 11 Sep 2019 16:50:00 +0200 (CEST) From: Philipp Puschmann To: linux-kernel@vger.kernel.org Subject: [PATCH 0/4] Fix UART DMA freezes for iMX6 Date: Wed, 11 Sep 2019 16:49:39 +0200 Message-Id: <20190911144943.21554-1-philipp.puschmann@emlix.com> X-Mailer: git-send-email 2.23.0 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190911_075005_027786_18358D20 X-CRM114-Status: GOOD ( 10.13 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-serial@vger.kernel.org, shawnguo@kernel.org, s.hauer@pengutronix.de, jslaby@suse.com, vkoul@kernel.org, linux-imx@nxp.com, kernel@pengutronix.de, gregkh@linuxfoundation.org, dmaengine@vger.kernel.org, dan.j.williams@intel.com, festevam@gmail.com, Philipp Puschmann , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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 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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel