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,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 B03CEC49ED7 for ; Mon, 16 Sep 2019 14:24:44 +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 8218020830 for ; Mon, 16 Sep 2019 14:24:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="AIRuPZU+" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8218020830 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=pengutronix.de 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:References:In-Reply-To: Date:To:From:Subject:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=viJCftj6n0fGwX9pTVEFMw/K//nuogK6KborJgO+mn4=; b=AIRuPZU+CudrFB YN2nxyNISbf6TJ/v+ANdq1PjNbkT5rQom5EbxYYWg8PUoDNJI3eavUWy6Gvo8vEICcaE9U4No1Xuy u+6EyMyVvsoXIbaClBzaihCKBouwfUHGCyfT9HWnnfdKWxAlC2AFHFrVrqj6NC4LFwXDtI9geqxuG 1aZdmk5E40E+eIRRJzPmzymke9JAPtC02WdLHhYd09uPORtFqMKv+Ov98IcFl5awmFwbgV/kPk3/b U+QWioTHpBbcnrIB2llITs074J3TQeCIyBGC9Y6D1kBDX1GzCvqziizFxhDf+ugoUTFITTaDSi/Pb WgjCFy3xgD4kPBiseRsg==; 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 1i9rvh-0008A0-5H; Mon, 16 Sep 2019 14:24:37 +0000 Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.92.2 #3 (Red Hat Linux)) id 1i9rvf-00089h-1t for linux-arm-kernel@lists.infradead.org; Mon, 16 Sep 2019 14:24:36 +0000 Received: from kresse.hi.pengutronix.de ([2001:67c:670:100:1d::2a]) by metis.ext.pengutronix.de with esmtp (Exim 4.92) (envelope-from ) id 1i9rvN-0002y0-MR; Mon, 16 Sep 2019 16:24:17 +0200 Message-ID: Subject: Re: [PATCH 3/4] serial: imx: adapt rx buffer and dma periods From: Lucas Stach To: Philipp Puschmann , linux-kernel@vger.kernel.org Date: Mon, 16 Sep 2019 16:24:17 +0200 In-Reply-To: <20190911144943.21554-4-philipp.puschmann@emlix.com> References: <20190911144943.21554-1-philipp.puschmann@emlix.com> <20190911144943.21554-4-philipp.puschmann@emlix.com> User-Agent: Evolution 3.30.5-1.1 MIME-Version: 1.0 X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::2a X-SA-Exim-Mail-From: l.stach@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-arm-kernel@lists.infradead.org X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190916_072435_099363_00E119C8 X-CRM114-Status: GOOD ( 14.14 ) 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: festevam@gmail.com, kernel@pengutronix.de, gregkh@linuxfoundation.org, s.hauer@pengutronix.de, vkoul@kernel.org, linux-imx@nxp.com, linux-serial@vger.kernel.org, jslaby@suse.com, dmaengine@vger.kernel.org, dan.j.williams@intel.com, shawnguo@kernel.org, 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 On Mi, 2019-09-11 at 16:49 +0200, Philipp Puschmann wrote: > 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 buffer is available. > While we have addressed the dma handling already 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 Reasoning seems sound: Reviewed-by: Lucas Stach > --- > 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 57d6e6ba556e..cdc51569237c 100644 > --- a/drivers/tty/serial/imx.c > +++ b/drivers/tty/serial/imx.c > @@ -1028,8 +1028,6 @@ 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. > @@ -1112,7 +1110,8 @@ 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) > { _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel