From patchwork Tue Mar 22 03:18:29 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Leizhen (ThunderTown)" X-Patchwork-Id: 8637801 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id D7AFBC0553 for ; Tue, 22 Mar 2016 03:20:17 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 029992034C for ; Tue, 22 Mar 2016 03:20:17 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3381320306 for ; Tue, 22 Mar 2016 03:20:16 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1aiCqG-0004ba-O2; Tue, 22 Mar 2016 03:18:48 +0000 Received: from szxga02-in.huawei.com ([119.145.14.65]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1aiCq6-0004VX-3o for linux-arm-kernel@lists.infradead.org; Tue, 22 Mar 2016 03:18:39 +0000 Received: from 172.24.1.47 (EHLO szxeml434-hub.china.huawei.com) ([172.24.1.47]) by szxrg02-dlp.huawei.com (MOS 4.3.7-GA FastPath queued) with ESMTP id DDY03680; Tue, 22 Mar 2016 11:17:16 +0800 (CST) Received: from localhost (10.177.23.164) by szxeml434-hub.china.huawei.com (10.82.67.225) with Microsoft SMTP Server id 14.3.235.1; Tue, 22 Mar 2016 11:17:08 +0800 From: Zhen Lei To: Catalin Marinas , Will Deacon , linux-arm-kernel , linux-kernel Subject: [PATCH v3 1/1] arm64/dma-mapping: reduce an unnecessary conversion for coherent DMA Date: Tue, 22 Mar 2016 11:18:29 +0800 Message-ID: <1458616709-21888-2-git-send-email-thunder.leizhen@huawei.com> X-Mailer: git-send-email 1.9.5.msysgit.1 In-Reply-To: <1458616709-21888-1-git-send-email-thunder.leizhen@huawei.com> References: <1458616709-21888-1-git-send-email-thunder.leizhen@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.177.23.164] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020202.56F0B943.006E, ss=1, re=0.000, recu=0.000, reip=0.000, cl=1, cld=1, fgs=0, ip=0.0.0.0, so=2013-06-18 04:22:30, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 46a84f2cbdd3496d96972dd097d6a7ec X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20160321_201838_560533_7A21E737 X-CRM114-Status: GOOD ( 14.43 ) X-Spam-Score: -4.2 (----) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Xinwei Hu , Zhen Lei , Zefan Li , Hanjun Guo , Tianhong Ding Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable 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 1.For coherent DMA In swiotlb_alloc_coherent, it directly return vaddr on success, and pass vaddr to free_pages on failure. So, we can directly transparent pass vaddr from __dma_free to swiotlb_free_coherent. According to my testing, it can save 8 clock cycles. 2.For non-coherent DMA. Keep no change for the original processing flow. Because all DDR memory mapped as cacheable by default. But for non-coherent devices, both CPUs and devices should use NC(non-cacheable) attributes to access memory, to keep consistency. So we can not directly use vaddr retured by __dma_alloc_coherent, but should further remap the physical memory as NC and return it. So in __dma_free, we first use the NC-vaddr to unmap, then get vaddr base upon dma_handle and use it to free memory back to buddy. Signed-off-by: Zhen Lei --- arch/arm64/mm/dma-mapping.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) -- 2.5.0 diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c index a6e757c..ceb2018 100644 --- a/arch/arm64/mm/dma-mapping.c +++ b/arch/arm64/mm/dma-mapping.c @@ -187,16 +187,22 @@ static void __dma_free(struct device *dev, size_t size, void *vaddr, dma_addr_t dma_handle, struct dma_attrs *attrs) { - void *swiotlb_addr = phys_to_virt(dma_to_phys(dev, dma_handle)); - size = PAGE_ALIGN(size); if (!is_device_dma_coherent(dev)) { if (__free_from_pool(vaddr, size)) return; vunmap(vaddr); + + /* + * For non-coherent DMA, the vaddr is not part of the linear + * mapping as it has been remapped by __dma_alloc() via + * dma_common_contiguous_remap(), hence for swiotlb freeing we + * need the actual linear map address. + */ + vaddr = phys_to_virt(dma_to_phys(dev, dma_handle)); } - __dma_free_coherent(dev, size, swiotlb_addr, dma_handle, attrs); + __dma_free_coherent(dev, size, vaddr, dma_handle, attrs); } static dma_addr_t __swiotlb_map_page(struct device *dev, struct page *page,