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 e15dab752d4c588544ccabdbe020a7cc092e23c8 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: Marek Szyprowski m.szyprowski@samsung.com --- drivers/media/v4l2-core/videobuf2-dma-contig.c | 87 ++++++++++++++++++++++-- 1 file changed, 82 insertions(+), 5 deletions(-)

diff --git a/drivers/media/v4l2-core/videobuf2-dma-contig.c b/drivers/media/v4l2-core/videobuf2-dma-contig.c index fd56f25..1382749 100644 --- a/drivers/media/v4l2-core/videobuf2-dma-contig.c +++ b/drivers/media/v4l2-core/videobuf2-dma-contig.c @@ -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;

- 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); + 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); + 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); +} +#elsif 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); +} +#elsif 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; }