From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754399Ab2ACRqv (ORCPT ); Tue, 3 Jan 2012 12:46:51 -0500 Received: from caramon.arm.linux.org.uk ([78.32.30.218]:55829 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753420Ab2ACRqt (ORCPT ); Tue, 3 Jan 2012 12:46:49 -0500 Date: Tue, 3 Jan 2012 17:46:39 +0000 From: Russell King - ARM Linux To: Richard Zhao Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, patches@linaro.org, vinod.koul@intel.com, eric.miao@linaro.org, kernel@pengutronix.de, dan.j.williams@intel.com, shawn.guo@linaro.org Subject: Re: [PATCH v2 2/2] dma/imx-sdma: add wmb before enable a channel Message-ID: <20120103174639.GF2914@n2100.arm.linux.org.uk> References: <1325428692-11473-1-git-send-email-richard.zhao@linaro.org> <1325428692-11473-3-git-send-email-richard.zhao@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1325428692-11473-3-git-send-email-richard.zhao@linaro.org> User-Agent: Mutt/1.5.19 (2009-01-05) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jan 01, 2012 at 10:38:12PM +0800, Richard Zhao wrote: > dma_alloc_coherent memory may be bufferable. We need to add > nececcary memory barrier. > > Signed-off-by: Richard Zhao > --- > drivers/dma/imx-sdma.c | 1 + > 1 files changed, 1 insertions(+), 0 deletions(-) > > diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c > index f8e87b5..9301bff 100644 > --- a/drivers/dma/imx-sdma.c > +++ b/drivers/dma/imx-sdma.c > @@ -394,6 +394,7 @@ static int sdma_config_ownership(struct sdma_channel *sdmac, > > static void sdma_enable_channel(struct sdma_engine *sdma, int channel) > { > + wmb(); > __raw_writel(1 << channel, sdma->regs + SDMA_H_START); Use writel(). That's what it's there for: #ifdef CONFIG_ARM_DMA_MEM_BUFFERABLE #define __iowmb() wmb() #endif #define writel_relaxed(v,c) ((void)__raw_writel((__force u32) \ cpu_to_le32(v),__mem_pci(c))) #define writel(v,c) ({ __iowmb(); writel_relaxed(v,c); })