From patchwork Thu Jan 2 15:11:11 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Russell King X-Patchwork-Id: 3425541 Return-Path: X-Original-To: patchwork-dmaengine@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id D91BB9F2E9 for ; Thu, 2 Jan 2014 15:15:47 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id B025420145 for ; Thu, 2 Jan 2014 15:15:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1C1E52015A for ; Thu, 2 Jan 2014 15:15:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752182AbaABPPX (ORCPT ); Thu, 2 Jan 2014 10:15:23 -0500 Received: from gw-1.arm.linux.org.uk ([78.32.30.217]:54169 "EHLO pandora.arm.linux.org.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751987AbaABPPW (ORCPT ); Thu, 2 Jan 2014 10:15:22 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=arm.linux.org.uk; s=pandora; h=Date:Sender:Message-Id:Subject:Cc:To:From:References:In-Reply-To; bh=ezkH6Ds+w6iE7m/6NRz7vVKHrW0UAw5zSeMqagFBo6o=; b=eBYbgoiNjBHpAbmkJNehAibwYKhMNQBzos5lOMMGo5Qmh2YkLYMxSvqy5E6JINq52rhKQ4tsqSz1gcxGcB+g3yb6sv1TSLK+C0j+gS8quZPpqzWQYNG+SMx4LG1nmEKomoalbboJLsN5iRuKc+8z3VpjXd3JFv6zygprOWczhlw=; Received: from [2001:4d48:ad52:3201:222:68ff:fe15:37dd] (port=56306 helo=rmk-PC.arm.linux.org.uk) by pandora.arm.linux.org.uk with esmtpsa (TLSv1:AES256-SHA:256) (Exim 4.76) (envelope-from ) id 1VyjvT-0003dD-IM; Thu, 02 Jan 2014 15:11:11 +0000 Received: from rmk by rmk-PC.arm.linux.org.uk with local (Exim 4.76) (envelope-from ) id 1VyjvT-0005Es-6A; Thu, 02 Jan 2014 15:11:11 +0000 In-Reply-To: <20140102150836.GA3826@n2100.arm.linux.org.uk> References: <20140102150836.GA3826@n2100.arm.linux.org.uk> From: Russell King To: dmaengine@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org Cc: Vinod Koul , Dan Williams Subject: [PATCH RFC 14/26] dmaengine: omap-dma: move barrier to omap_dma_start_desc() Message-Id: Date: Thu, 02 Jan 2014 15:11:11 +0000 Sender: dmaengine-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org X-Spam-Status: No, score=-7.3 required=5.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,RP_MATCHES_RCVD,T_DKIM_INVALID,UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP We don't need to issue a barrier for every segment of a DMA transfer; doing this just once per descriptor will do. Signed-off-by: Russell King --- drivers/dma/omap-dma.c | 8 +++++++- 1 files changed, 7 insertions(+), 1 deletions(-) diff --git a/drivers/dma/omap-dma.c b/drivers/dma/omap-dma.c index bdea85802b5b..e212e0df9b42 100644 --- a/drivers/dma/omap-dma.c +++ b/drivers/dma/omap-dma.c @@ -194,7 +194,6 @@ static void omap_dma_start(struct omap_chan *c, struct omap_desc *d) val = c->plat->dma_read(CCR, c->dma_ch); val |= CCR_ENABLE; - mb(); c->plat->dma_write(val, CCR, c->dma_ch); } @@ -301,6 +300,13 @@ static void omap_dma_start_desc(struct omap_chan *c) c->desc = d = to_omap_dma_desc(&vd->tx); c->sgidx = 0; + /* + * This provides the necessary barrier to ensure data held in + * DMA coherent memory is visible to the DMA engine prior to + * the transfer starting. + */ + mb(); + c->plat->dma_write(d->ccr, CCR, c->dma_ch); if (dma_omap1()) c->plat->dma_write(d->ccr >> 16, CCR2, c->dma_ch);