From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755133Ab3ADQKn (ORCPT ); Fri, 4 Jan 2013 11:10:43 -0500 Received: from mail.free-electrons.com ([94.23.32.191]:35337 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755062Ab3ADQKl (ORCPT ); Fri, 4 Jan 2013 11:10:41 -0500 Date: Fri, 4 Jan 2013 17:10:33 +0100 From: Thomas Petazzoni To: Lubomir Rintel Cc: Dan Williams , Vinod Koul , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH 2/2] dma: mv_xor: do not sync the DMA buffer after being deallocated Message-ID: <20130104171033.4a244c3d@skate> In-Reply-To: <1356636228-23096-2-git-send-email-lkundrak@v3.sk> References: <1356636228-23096-1-git-send-email-lkundrak@v3.sk> <1356636228-23096-2-git-send-email-lkundrak@v3.sk> Organization: Free Electrons X-Mailer: Claws Mail 3.9.0 (GTK+ 2.24.10; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dear Lubomir Rintel, On Thu, 27 Dec 2012 20:23:48 +0100, Lubomir Rintel wrote: > dma_sync_single_for_cpu(dma_chan->device->dev, dest_dma, > MV_XOR_TEST_SIZE, DMA_FROM_DEVICE); > + dma_unmap_single(dma_chan->device->dev, dest_dma, MV_XOR_TEST_SIZE, > + DMA_FROM_DEVICE); I would assume that dma_unmap_single() implies a dma_sync_single_for_cpu() since you're unmapping the DMA buffer. So if you use dma_unmap_single(), I think you can remove the call to dma_sync_single_for_cpu(). > dma_sync_single_for_cpu(dma_chan->device->dev, dest_dma, > PAGE_SIZE, DMA_FROM_DEVICE); > + dma_unmap_page(dma_chan->device->dev, dest_dma, PAGE_SIZE, > + DMA_FROM_DEVICE); Ditto. Also, the mv_xor_memcpy_self_test() function not only dma_map_single() the destination buffer, but also the source buffer. So presumably, the source buffer should also be dma_unmap_single()'d. And for the mv_xor_xor_self_test() function, multiple source buffers are dma_map_page()'d, so they should all be dma_unmap_page()'d I guess, not only the destination buffer. Does that make sense? Thanks, Thomas -- Thomas Petazzoni, Free Electrons Kernel, drivers, real-time and embedded Linux development, consulting, training and support. http://free-electrons.com