From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751917AbaHHX0E (ORCPT ); Fri, 8 Aug 2014 19:26:04 -0400 Received: from smtp.codeaurora.org ([198.145.11.231]:38841 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750853AbaHHX0B (ORCPT ); Fri, 8 Aug 2014 19:26:01 -0400 Message-ID: <53E55C86.3040705@codeaurora.org> Date: Fri, 08 Aug 2014 16:25:58 -0700 From: Laura Abbott User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: Andrew Morton CC: David Riley , Arnd Bergmann , Catalin Marinas , Will Deacon , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Thierry Reding , Ritesh Harjain , Russell King , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCHv6 3/5] common: dma-mapping: Introduce common remapping functions References: <1407529397-6642-1-git-send-email-lauraa@codeaurora.org> <1407529397-6642-3-git-send-email-lauraa@codeaurora.org> <20140808154556.11c7bf68d1bcf2714c148e3b@linux-foundation.org> In-Reply-To: <20140808154556.11c7bf68d1bcf2714c148e3b@linux-foundation.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/8/2014 3:45 PM, Andrew Morton wrote: > On Fri, 8 Aug 2014 13:23:15 -0700 Laura Abbott wrote: > >> >> For architectures without coherent DMA, memory for DMA may >> need to be remapped with coherent attributes. Factor out >> the the remapping code from arm and put it in a >> common location to reduce code duplication. >> >> As part of this, the arm APIs are now migrated away from >> ioremap_page_range to the common APIs which use map_vm_area for remapping. >> This should be an equivalent change and using map_vm_area is more >> correct as ioremap_page_range is intended to bring in io addresses >> into the cpu space and not regular kernel managed memory. >> >> ... >> >> @@ -267,3 +269,68 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma, >> return ret; >> } >> EXPORT_SYMBOL(dma_common_mmap); >> + >> +/* >> + * remaps an allocated contiguous region into another vm_area. >> + * Cannot be used in non-sleeping contexts >> + */ >> + >> +void *dma_common_contiguous_remap(struct page *page, size_t size, >> + unsigned long vm_flags, >> + pgprot_t prot, const void *caller) >> +{ >> + int i; >> + struct page **pages; >> + void *ptr; >> + >> + pages = kmalloc(sizeof(struct page *) << get_order(size), GFP_KERNEL); >> + if (!pages) >> + return NULL; >> + >> + for (i = 0; i < (size >> PAGE_SHIFT); i++) >> + pages[i] = page + i; > > Assumes a single mem_map[] array. That's not the case for sparsemem > (at least). > > Good point. I guess the best option is to increment via pfn and call pfn_to_page. Either that or go back to slightly abusing ioremap_page_range to remap normal memory. Thanks, Laura -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation