From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753131AbdBUNHy (ORCPT ); Tue, 21 Feb 2017 08:07:54 -0500 Received: from foss.arm.com ([217.140.101.70]:60382 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752529AbdBUNHm (ORCPT ); Tue, 21 Feb 2017 08:07:42 -0500 Subject: Re: [PATCH 1/7] dma: Take into account dma_pfn_offset To: Vladimir Murzin , linux-arm-kernel@lists.infradead.org References: <1487152792-34214-1-git-send-email-vladimir.murzin@arm.com> <1487152792-34214-2-git-send-email-vladimir.murzin@arm.com> Cc: kbuild-all@01.org, linux@armlinux.org.uk, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, Joerg Roedel , Christian Borntraeger From: Robin Murphy Message-ID: Date: Tue, 21 Feb 2017 13:07:38 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 MIME-Version: 1.0 In-Reply-To: <1487152792-34214-2-git-send-email-vladimir.murzin@arm.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 15/02/17 09:59, Vladimir Murzin wrote: > Even though dma-noop-ops assumes 1:1 memory mapping DMA memory range > can be different to RAM. For example, ARM STM32F4 MCU offers the > possibility to remap SDRAM from 0xc000_0000 to 0x0 to get CPU > performance boost, but DMA continue to see SDRAM at 0xc000_0000. This > difference in mapping is handled via device-tree "dma-range" property > which leads to dev->dma_pfn_offset is set nonzero. To handle such > cases take dma_pfn_offset into account. Modulo trivial style nits (include order, line length) which I'll leave for others to object to if they wish, this looks correct to me. Reviewed-by: Robin Murphy > Cc: Joerg Roedel > Cc: Christian Borntraeger > Reported-by: Benjamin Gaignard > Tested-by: Benjamin Gaignard > Tested-by: Andras Szemzo > Tested-by: Alexandre TORGUE > Signed-off-by: Vladimir Murzin > --- > lib/dma-noop.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/lib/dma-noop.c b/lib/dma-noop.c > index 3d766e7..a14eee5 100644 > --- a/lib/dma-noop.c > +++ b/lib/dma-noop.c > @@ -7,6 +7,7 @@ > #include > #include > #include > +#include > > static void *dma_noop_alloc(struct device *dev, size_t size, > dma_addr_t *dma_handle, gfp_t gfp, > @@ -16,7 +17,8 @@ static void *dma_noop_alloc(struct device *dev, size_t size, > > ret = (void *)__get_free_pages(gfp, get_order(size)); > if (ret) > - *dma_handle = virt_to_phys(ret); > + *dma_handle = virt_to_phys(ret) - PFN_PHYS(dev->dma_pfn_offset); > + > return ret; > } > > @@ -32,7 +34,7 @@ static dma_addr_t dma_noop_map_page(struct device *dev, struct page *page, > enum dma_data_direction dir, > unsigned long attrs) > { > - return page_to_phys(page) + offset; > + return page_to_phys(page) + offset - PFN_PHYS(dev->dma_pfn_offset); > } > > static int dma_noop_map_sg(struct device *dev, struct scatterlist *sgl, int nents, > @@ -47,7 +49,7 @@ static int dma_noop_map_sg(struct device *dev, struct scatterlist *sgl, int nent > > BUG_ON(!sg_page(sg)); > va = sg_virt(sg); > - sg_dma_address(sg) = (dma_addr_t)virt_to_phys(va); > + sg_dma_address(sg) = (dma_addr_t)(virt_to_phys(va) - PFN_PHYS(dev->dma_pfn_offset)); > sg_dma_len(sg) = sg->length; > } > >