Messages in this thread Patch in this message | | | From | Jacopo Mondi <> | Subject | [RFC v2 2/2] base: dma-mapping: Postpone page_to_pfn() on mmap() | Date | Tue, 14 Nov 2017 18:08:06 +0100 |
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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 <laurent.pinchart@ideasonboard.com> Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org> --- 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
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