On 15/02/17 09:59, Vladimir Murzin wrote:
> Even though dma-noop-ops assumes 1:1 memory mapping DMA memory range
> can be different to RAM. For example, ARM STM32F4 MCU offers the
> possibility to remap SDRAM from 0xc000_0000 to 0x0 to get CPU
> performance boost, but DMA continue to see SDRAM at 0xc000_0000. This
> difference in mapping is handled via device-tree "dma-range" property
> which leads to dev->dma_pfn_offset is set nonzero. To handle such
> cases take dma_pfn_offset into account.
Modulo trivial style nits (include order, line length) which I'll leave
for others to object to if they wish, this looks correct to me.
Reviewed-by: Robin Murphy <robin.mur...@arm.com>
> Cc: Joerg Roedel <jroe...@suse.de>
> Cc: Christian Borntraeger <borntrae...@de.ibm.com>
> Reported-by: Benjamin Gaignard <benjamin.gaign...@linaro.org>
> Tested-by: Benjamin Gaignard <benjamin.gaign...@linaro.org>
> Tested-by: Andras Szemzo <s...@esh.hu>
> Tested-by: Alexandre TORGUE <alexandre.tor...@st.com>
> Signed-off-by: Vladimir Murzin <vladimir.mur...@arm.com>
> ---
> lib/dma-noop.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/lib/dma-noop.c b/lib/dma-noop.c
> index 3d766e7..a14eee5 100644
> --- a/lib/dma-noop.c
> +++ b/lib/dma-noop.c
> @@ -7,6 +7,7 @@
> #include <linux/mm.h>
> #include <linux/dma-mapping.h>
> #include <linux/scatterlist.h>
> +#include <linux/pfn.h>
>
> static void *dma_noop_alloc(struct device *dev, size_t size,
> dma_addr_t *dma_handle, gfp_t gfp,
> @@ -16,7 +17,8 @@ static void *dma_noop_alloc(struct device *dev, size_t size,
>
> ret = (void *)__get_free_pages(gfp, get_order(size));
> if (ret)
> - *dma_handle = virt_to_phys(ret);
> + *dma_handle = virt_to_phys(ret) - PFN_PHYS(dev->dma_pfn_offset);
> +
> return ret;
> }
>
> @@ -32,7 +34,7 @@ static dma_addr_t dma_noop_map_page(struct device *dev,
> struct page *page,
> enum dma_data_direction dir,
> unsigned long attrs)
> {
> - return page_to_phys(page) + offset;
> + return page_to_phys(page) + offset - PFN_PHYS(dev->dma_pfn_offset);
> }
>
> static int dma_noop_map_sg(struct device *dev, struct scatterlist *sgl, int
> nents,
> @@ -47,7 +49,7 @@ static int dma_noop_map_sg(struct device *dev, struct
> scatterlist *sgl, int nent
>
> BUG_ON(!sg_page(sg));
> va = sg_virt(sg);
> - sg_dma_address(sg) = (dma_addr_t)virt_to_phys(va);
> + sg_dma_address(sg) = (dma_addr_t)(virt_to_phys(va) -
> PFN_PHYS(dev->dma_pfn_offset));
> sg_dma_len(sg) = sg->length;
> }
>
>
