On 21/02/17 13:07, Robin Murphy wrote:
> 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>
Much appreciated!
Vladimir
>
>> 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;
>> }
>>
>>
>
>
