Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755829Ab3EQMUv (ORCPT ); Fri, 17 May 2013 08:20:51 -0400 Received: from mail-ie0-f177.google.com ([209.85.223.177]:33539 "EHLO mail-ie0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755343Ab3EQMUt convert rfc822-to-8bit (ORCPT ); Fri, 17 May 2013 08:20:49 -0400 MIME-Version: 1.0 In-Reply-To: <201305152231.52423.heiko@sntech.de> References: <201305111330.05046.heiko@sntech.de> <201305111331.25405.heiko@sntech.de> <201305152231.52423.heiko@sntech.de> Date: Fri, 17 May 2013 14:20:49 +0200 Message-ID: Subject: Re: [RFC 2/4] dma: add dmaengine driver for Samsung s3c24xx SoCs From: Linus Walleij To: =?ISO-8859-1?Q?Heiko_St=FCbner?= Cc: Dan Williams , Vinod Koul , "linux-kernel@vger.kernel.org" , linux-samsung-soc , Kukjin Kim , "linux-arm-kernel@lists.infradead.org" , Russell King - ARM Linux Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1092 Lines: 27 On Wed, May 15, 2013 at 10:31 PM, Heiko St?bner wrote: > If I understand the writel semantics and the thread from you from 2011 [0] > correctly, only the writel to DMASKTRIG mustn't be relaxed to make sure the > settings registers are written to before, so like: > > writel_relaxed(txd->src_addr, phy->base + DISRC); > writel_relaxed(txd->disrcc, phy->base + DISRCC); > writel_relaxed(txd->dst_addr, phy->base + DIDST); > writel_relaxed(txd->didstc, phy->base + DIDSTC); > writel_relaxed(dcon, phy->base + DCON); > > val = readl_relaxed(phy->base + DMASKTRIG); > val &= ~DMASKTRIG_STOP; > val |= DMASKTRIG_ON; > writel(val, phy->base + DMASKTRIG); Yep. That will drain write buffers etc and make sure all outstanding writes hit the hardware. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/