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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 19587C3A5A6 for ; Thu, 19 Sep 2019 10:26:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EBF722196E for ; Thu, 19 Sep 2019 10:26:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731539AbfISK0t (ORCPT ); Thu, 19 Sep 2019 06:26:49 -0400 Received: from mx1.emlix.com ([188.40.240.192]:57624 "EHLO mx1.emlix.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388156AbfISK0t (ORCPT ); Thu, 19 Sep 2019 06:26:49 -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 EF3CC603CA; Thu, 19 Sep 2019 12:26:46 +0200 (CEST) From: Philipp Puschmann To: linux-kernel@vger.kernel.org Cc: gregkh@linuxfoundation.org, yibin.gong@nxp.com, fugang.duan@nxp.com, l.stach@pengutronix.de, jslaby@suse.com, shawnguo@kernel.org, s.hauer@pengutronix.de, kernel@pengutronix.de, festevam@gmail.com, linux-imx@nxp.com, linux-serial@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Philipp Puschmann Subject: [PATCH v2] serial: imx: adapt rx buffer and dma periods Date: Thu, 19 Sep 2019 12:26:28 +0200 Message-Id: <20190919102628.23621-1-philipp.puschmann@emlix.com> X-Mailer: git-send-email 2.23.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Using only 4 DMA periods for UART RX is very few if we have a high frequency of small transfers - like in our case using Bluetooth with many small packets via UART - causing many dma transfers but in each only filling a fraction of a single buffer. Such a case may lead to the situation that DMA RX transfer is triggered but no free buffer is available. While we have addressed the dma handling already with "dmaengine: imx-sdma: fix dma freezes" we still want to avoid UART RX FIFO overrun. So we decrease the size of the buffers and increase their number and the total buffer size. Signed-off-by: Philipp Puschmann Reviewed-by: Lucas Stach --- Changelog v2: - split this patch from series "Fix UART DMA freezes for iMX6" - add Reviewed-by tag drivers/tty/serial/imx.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 87c58f9f6390..51dc19833eab 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -1034,8 +1034,6 @@ static void imx_uart_timeout(struct timer_list *t) } } -#define RX_BUF_SIZE (PAGE_SIZE) - /* * There are two kinds of RX DMA interrupts(such as in the MX6Q): * [1] the RX DMA buffer is full. @@ -1118,7 +1116,8 @@ static void imx_uart_dma_rx_callback(void *data) } /* RX DMA buffer periods */ -#define RX_DMA_PERIODS 4 +#define RX_DMA_PERIODS 16 +#define RX_BUF_SIZE (PAGE_SIZE / 4) static int imx_uart_start_rx_dma(struct imx_port *sport) { -- 2.23.0