Commit 774d2301 authored by Marek Szyprowski's avatar Marek Szyprowski Committed by Mauro Carvalho Chehab
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[media] videobuf2-dc: Fix support for mappings without struct page in userptr mode 



Earlier version of dma-contig allocator in user ptr mode assumed that in
all cases DMA address equals physical address. This was just a special case.
Commit e15dab75 introduced correct support
for converting userpage to dma address, but unfortunately it broke the
support for simple dma address = physical address for the case, when given
physical frame has no struct page associated with it (this happens if one
use for example dma_declare_coherent api or other reserved memory approach).
This commit restores support for such cases.

Signed-off-by: default avatarMarek Szyprowski <m.szyprowski@samsung.com>
[s.nawrocki@samsung.com: replaced #elsif with #elif]
Signed-off-by: default avatarSylwester Nawrocki <s.nawrocki@samsung.com>

Signed-off-by: default avatarMauro Carvalho Chehab <m.chehab@samsung.com>
parent 3c5c23c5

drivers/media/v4l2-core/videobuf2-dma-contig.c

+82 −5
Original line number Diff line number Diff line
@@ -423,6 +423,39 @@ static inline int vma_is_io(struct vm_area_struct *vma) 
	return !!(vma->vm_flags & (VM_IO | VM_PFNMAP));

}



static int vb2_dc_get_user_pfn(unsigned long start, int n_pages,

	struct vm_area_struct *vma, unsigned long *res)

{

	unsigned long pfn, start_pfn, prev_pfn;

	unsigned int i;

	int ret;



	if (!vma_is_io(vma))

		return -EFAULT;



	ret = follow_pfn(vma, start, &pfn);

	if (ret)

		return ret;



	start_pfn = pfn;

	start += PAGE_SIZE;



	for (i = 1; i < n_pages; ++i, start += PAGE_SIZE) {

		prev_pfn = pfn;

		ret = follow_pfn(vma, start, &pfn);



		if (ret) {

			pr_err("no page for address %lu\n", start);

			return ret;

		}

		if (pfn != prev_pfn + 1)

			return -EINVAL;

	}



	*res = start_pfn;

	return 0;

}



static int vb2_dc_get_user_pages(unsigned long start, struct page **pages,

	int n_pages, struct vm_area_struct *vma, int write)

{
@@ -433,6 +466,9 @@ static int vb2_dc_get_user_pages(unsigned long start, struct page **pages, 
			unsigned long pfn;

			int ret = follow_pfn(vma, start, &pfn);



			if (!pfn_valid(pfn))

				return -EINVAL;



			if (ret) {

				pr_err("no page for address %lu\n", start);

				return ret;
@@ -468,16 +504,49 @@ static void vb2_dc_put_userptr(void *buf_priv) 
	struct vb2_dc_buf *buf = buf_priv;

	struct sg_table *sgt = buf->dma_sgt;



	if (sgt) {

		dma_unmap_sg(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir);

		if (!vma_is_io(buf->vma))

			vb2_dc_sgt_foreach_page(sgt, vb2_dc_put_dirty_page);



		sg_free_table(sgt);

		kfree(sgt);

	}

	vb2_put_vma(buf->vma);

	kfree(buf);

}



/*

 * For some kind of reserved memory there might be no struct page available,

 * so all that can be done to support such 'pages' is to try to convert

 * pfn to dma address or at the last resort just assume that

 * dma address == physical address (like it has been assumed in earlier version

 * of videobuf2-dma-contig

 */



#ifdef __arch_pfn_to_dma

static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn)

{

	return (dma_addr_t)__arch_pfn_to_dma(dev, pfn);

}

#elif defined(__pfn_to_bus)

static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn)

{

	return (dma_addr_t)__pfn_to_bus(pfn);

}

#elif defined(__pfn_to_phys)

static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn)

{

	return (dma_addr_t)__pfn_to_phys(pfn);

}

#else

static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn)

{

	/* really, we cannot do anything better at this point */

	return (dma_addr_t)(pfn) << PAGE_SHIFT;

}

#endif



static void *vb2_dc_get_userptr(void *alloc_ctx, unsigned long vaddr,

	unsigned long size, int write)

{
@@ -548,6 +617,14 @@ static void *vb2_dc_get_userptr(void *alloc_ctx, unsigned long vaddr, 
	/* extract page list from userspace mapping */

	ret = vb2_dc_get_user_pages(start, pages, n_pages, vma, write);

	if (ret) {

		unsigned long pfn;

		if (vb2_dc_get_user_pfn(start, n_pages, vma, &pfn) == 0) {

			buf->dma_addr = vb2_dc_pfn_to_dma(buf->dev, pfn);

			buf->size = size;

			kfree(pages);

			return buf;

		}



		pr_err("failed to get user pages\n");

		goto fail_vma;

	}

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