Re: [PATCH 16/31] s390: handle page-less SG entries

Sebastian Ott
2015-08-12T11:51:58Z

On Wed, 12 Aug 2015, Christoph Hellwig wrote:

> Use sg_phys() instead of page_to_phys(sg_page(sg)) so that we don't
> require a page structure for all DMA memory.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Acked-by: Sebastian Ott <sebott@linux.vnet.ibm.com>

> ---
> arch/s390/pci/pci_dma.c | 20 ++++++++++++++------
> 1 file changed, 14 insertions(+), 6 deletions(-)
>
> diff --git a/arch/s390/pci/pci_dma.c b/arch/s390/pci/pci_dma.c
> index 6fd8d58..aae5a47 100644
> --- a/arch/s390/pci/pci_dma.c
> +++ b/arch/s390/pci/pci_dma.c
> @@ -272,14 +272,13 @@ int dma_set_mask(struct device *dev, u64 mask)
> }
> EXPORT_SYMBOL_GPL(dma_set_mask);
>
> -static dma_addr_t s390_dma_map_pages(struct device *dev, struct page *page,
> - unsigned long offset, size_t size,
> +static dma_addr_t s390_dma_map_phys(struct device *dev, unsigned long pa,
> + size_t size,
> enum dma_data_direction direction,
> struct dma_attrs *attrs)
> {
> struct zpci_dev *zdev = get_zdev(to_pci_dev(dev));
> unsigned long nr_pages, iommu_page_index;
> - unsigned long pa = page_to_phys(page) + offset;
> int flags = ZPCI_PTE_VALID;
> dma_addr_t dma_addr;
>
> @@ -301,7 +300,7 @@ static dma_addr_t s390_dma_map_pages(struct device *dev, struct page *page,
>
> if (!dma_update_trans(zdev, pa, dma_addr, size, flags)) {
> atomic64_add(nr_pages, &zdev->mapped_pages);
> - return dma_addr + (offset & ~PAGE_MASK);
> + return dma_addr + (pa & ~PAGE_MASK);
> }
>
> out_free:
> @@ -312,6 +311,16 @@ out_err:
> return DMA_ERROR_CODE;
> }
>
> +static dma_addr_t s390_dma_map_pages(struct device *dev, struct page *page,
> + unsigned long offset, size_t size,
> + enum dma_data_direction direction,
> + struct dma_attrs *attrs)
> +{
> + unsigned long pa = page_to_phys(page) + offset;
> +
> + return s390_dma_map_phys(dev, pa, size, direction, attrs);
> +}
> +
> static void s390_dma_unmap_pages(struct device *dev, dma_addr_t dma_addr,
> size_t size, enum dma_data_direction direction,
> struct dma_attrs *attrs)
> @@ -384,8 +393,7 @@ static int s390_dma_map_sg(struct device *dev, struct scatterlist *sg,
> int i;
>
> for_each_sg(sg, s, nr_elements, i) {
> - struct page *page = sg_page(s);
> - s->dma_address = s390_dma_map_pages(dev, page, s->offset,
> + s->dma_address = s390_dma_map_phys(dev, sg_phys(s),
> s->length, dir, NULL);
> if (!dma_mapping_error(dev, s->dma_address)) {
> s->dma_length = s->length;
> --
> 1.9.1
>
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