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.
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>
Reviewed-by: Robin Murphy <robin.mur...@arm.com>
Signed-off-by: Vladimir Murzin <vladimir.mur...@arm.com>
---
lib/dma-noop.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/lib/dma-noop.c b/lib/dma-noop.c
index de26c8b..1f60c8a 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,
@@ -43,11 +45,12 @@ static int dma_noop_map_sg(struct device *dev, struct
scatterlist *sgl, int nent
struct scatterlist *sg;
for_each_sg(sgl, sg, nents, i) {
+ dma_addr_t offset = PFN_PHYS(dev->dma_pfn_offset);
void *va;
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) - offset;
sg_dma_len(sg) = sg->length;
}
--
2.0.0
