From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751151Ab2AAHOg (ORCPT ); Sun, 1 Jan 2012 02:14:36 -0500 Received: from metis.ext.pengutronix.de ([92.198.50.35]:48288 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750792Ab2AAHOe (ORCPT ); Sun, 1 Jan 2012 02:14:34 -0500 Date: Sun, 1 Jan 2012 08:14:25 +0100 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= To: Richard Zhao Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kernel@pengutronix.de, shawn.guo@linaro.org, vinod.koul@intel.com, dan.j.williams@intel.com, eric.miao@linaro.org, patches@linaro.org Subject: Re: [PATCH] dma/imx-sdma: add wmb before enable/run a channel Message-ID: <20120101071425.GA25978@pengutronix.de> References: <1325388460-20678-1-git-send-email-richard.zhao@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1325388460-20678-1-git-send-email-richard.zhao@linaro.org> User-Agent: Mutt/1.5.21 (2010-09-15) X-SA-Exim-Connect-IP: 2001:6f8:1178:2:21e:67ff:fe11:9c5c X-SA-Exim-Mail-From: ukl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Richard, On Sun, Jan 01, 2012 at 11:27:40AM +0800, Richard Zhao wrote: > dma_alloc_coherent memory may be bufferable. We need to add > nececcary memory barrier. necessary > > Signed-off-by: Richard Zhao > --- > drivers/dma/imx-sdma.c | 2 ++ > 1 files changed, 2 insertions(+), 0 deletions(-) > > diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c > index 2ebb2bc..8cd9492 100644 > --- a/drivers/dma/imx-sdma.c > +++ b/drivers/dma/imx-sdma.c > @@ -403,6 +403,7 @@ static int sdma_run_channel(struct sdma_channel *sdmac) > > init_completion(&sdmac->done); > > + wmb(); > __raw_writel(1 << channel, sdma->regs + SDMA_H_START); > > ret = wait_for_completion_timeout(&sdmac->done, HZ); > @@ -809,6 +810,7 @@ out: > > static void sdma_enable_channel(struct sdma_engine *sdma, int channel) > { > + wmb(); > __raw_writel(1 << channel, sdma->regs + SDMA_H_START); > } I don't know the sdma code very well, but wouldn't it be nice to call sdma_enable_channel() in sdma_run_channel() instead of open coding it? As you probably need some rearrangements to have sdma_enable_channel() declared in sdma_run_channel() this might be better done with a seperate patch. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ |