From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jacopo Mondi Date: Tue, 14 Nov 2017 17:08:06 +0000 Subject: [RFC v2 2/2] base: dma-mapping: Postpone page_to_pfn() on mmap() Message-Id: <1510679286-6988-3-git-send-email-jacopo+renesas@jmondi.org> List-Id: References: <1510679286-6988-1-git-send-email-jacopo+renesas@jmondi.org> In-Reply-To: <1510679286-6988-1-git-send-email-jacopo+renesas@jmondi.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: ysato@users.sourceforge.jp, dalias@libc.org, laurent.pinchart@ideasonboard.com, geert@linux-m68k.org Cc: Jacopo Mondi , linux-sh@vger.kernel.org, linux-renesas-soc@vger.kernel.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org On SH4 architecture, with SPARSEMEM memory model, translating page to pfn hangs the CPU. Post-pone translation to pfn after dma_mmap_from_dev_coherent() function call as it succeeds and make page translation not necessary. This patch was suggested by Laurent Pinchart and he's working to submit a proper fix mainline. Not sending for inclusion at the moment. Suggested-by: Laurent Pinchart Signed-off-by: Jacopo Mondi --- drivers/base/dma-mapping.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/base/dma-mapping.c b/drivers/base/dma-mapping.c index e584edd..73d64d3 100644 --- a/drivers/base/dma-mapping.c +++ b/drivers/base/dma-mapping.c @@ -227,8 +227,8 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma, #ifndef CONFIG_ARCH_NO_COHERENT_DMA_MMAP unsigned long user_count = vma_pages(vma); unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT; - unsigned long pfn = page_to_pfn(virt_to_page(cpu_addr)); unsigned long off = vma->vm_pgoff; + unsigned long pfn; vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); @@ -236,6 +236,7 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma, return ret; if (off < count && user_count <= (count - off)) { + pfn = page_to_pfn(virt_to_page(cpu_addr)); ret = remap_pfn_range(vma, vma->vm_start, pfn + off, user_count << PAGE_SHIFT, -- 2.7.4 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756029AbdKNRIf (ORCPT ); Tue, 14 Nov 2017 12:08:35 -0500 Received: from relay4-d.mail.gandi.net ([217.70.183.196]:57659 "EHLO relay4-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756005AbdKNRIZ (ORCPT ); Tue, 14 Nov 2017 12:08:25 -0500 From: Jacopo Mondi To: ysato@users.sourceforge.jp, dalias@libc.org, laurent.pinchart@ideasonboard.com, geert@linux-m68k.org Cc: Jacopo Mondi , linux-sh@vger.kernel.org, linux-renesas-soc@vger.kernel.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: [RFC v2 2/2] base: dma-mapping: Postpone page_to_pfn() on mmap() Date: Tue, 14 Nov 2017 18:08:06 +0100 Message-Id: <1510679286-6988-3-git-send-email-jacopo+renesas@jmondi.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1510679286-6988-1-git-send-email-jacopo+renesas@jmondi.org> References: <1510679286-6988-1-git-send-email-jacopo+renesas@jmondi.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On SH4 architecture, with SPARSEMEM memory model, translating page to pfn hangs the CPU. Post-pone translation to pfn after dma_mmap_from_dev_coherent() function call as it succeeds and make page translation not necessary. This patch was suggested by Laurent Pinchart and he's working to submit a proper fix mainline. Not sending for inclusion at the moment. Suggested-by: Laurent Pinchart Signed-off-by: Jacopo Mondi --- drivers/base/dma-mapping.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/base/dma-mapping.c b/drivers/base/dma-mapping.c index e584edd..73d64d3 100644 --- a/drivers/base/dma-mapping.c +++ b/drivers/base/dma-mapping.c @@ -227,8 +227,8 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma, #ifndef CONFIG_ARCH_NO_COHERENT_DMA_MMAP unsigned long user_count = vma_pages(vma); unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT; - unsigned long pfn = page_to_pfn(virt_to_page(cpu_addr)); unsigned long off = vma->vm_pgoff; + unsigned long pfn; vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); @@ -236,6 +236,7 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma, return ret; if (off < count && user_count <= (count - off)) { + pfn = page_to_pfn(virt_to_page(cpu_addr)); ret = remap_pfn_range(vma, vma->vm_start, pfn + off, user_count << PAGE_SHIFT, -- 2.7.4