Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756071AbbLDKuH (ORCPT ); Fri, 4 Dec 2015 05:50:07 -0500 Received: from foss.arm.com ([217.140.101.70]:53406 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752191AbbLDKuF (ORCPT ); Fri, 4 Dec 2015 05:50:05 -0500 Date: Fri, 4 Dec 2015 10:50:01 +0000 From: Catalin Marinas To: Brian Starkey Cc: gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Dan Williams , Arnd Bergmann Subject: Re: [PATCH] drivers: dma-coherent: use ioremap_wc() for DMA_MEMORY_MAP Message-ID: <20151204105000.GD10123@e104818-lin.cambridge.arm.com> References: <1448029226-4914-1-git-send-email-brian.starkey@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1448029226-4914-1-git-send-email-brian.starkey@arm.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1497 Lines: 37 On Fri, Nov 20, 2015 at 02:20:26PM +0000, Brian Starkey wrote: > When the DMA_MEMORY_MAP flag is used, memory which can be accessed > directly should be returned, so use ioremap_wc() instead of ioremap(). > Also, ensure that the correct memset operation is used in > dma_alloc_from_coherent() with respect to the region's flags. > > This fixes the below alignment fault on arm64, caused by invalid use > of memset() on Device memory. This is indeed affecting both arm32 and arm64 systems. > diff --git a/drivers/base/dma-coherent.c b/drivers/base/dma-coherent.c > index 55b8398..45358d0 100644 > --- a/drivers/base/dma-coherent.c > +++ b/drivers/base/dma-coherent.c > @@ -31,7 +31,10 @@ static int dma_init_coherent_memory(phys_addr_t phys_addr, dma_addr_t device_add > if (!size) > goto out; > > - mem_base = ioremap(phys_addr, size); > + if (flags & DMA_MEMORY_MAP) > + mem_base = ioremap_wc(phys_addr, size); > + else > + mem_base = ioremap(phys_addr, size); I wonder whether a memremap() approach for the DMA_MEMORY_MAP case would be better. This API was added recently by commit 92281dee825f ("arch: introduce memremap()"). It only supports write-back and write-through but we could add a MEMREMAP_WC flag for this case. -- Catalin -- 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/