Hello,
On Thursday, March 29, 2012 9:19 AM Hiroshi Doyu wrote:
On Wed, 29 Feb 2012 16:04:22 +0100
Marek Szyprowski m.szyprow...@samsung.com wrote:
This patch add a complete implementation of DMA-mapping API for
devices that have IOMMU support. All DMA-mapping calls are supported.
This patch contains some of the code kindly provided by Krishna Reddy
vdu...@nvidia.com and Andrzej Pietrasiewicz andrze...@samsung.com
Signed-off-by: Marek Szyprowski m.szyprow...@samsung.com
Signed-off-by: Kyungmin Park kyungmin.p...@samsung.com
Reviewed-by: Konrad Rzeszutek Wilk konrad.w...@oracle.com
---
arch/arm/Kconfig |8 +
arch/arm/include/asm/device.h|3 +
arch/arm/include/asm/dma-iommu.h | 34 ++
arch/arm/mm/dma-mapping.c| 726
+-
arch/arm/mm/vmregion.h |2 +-
5 files changed, 758 insertions(+), 15 deletions(-)
create mode 100644 arch/arm/include/asm/dma-iommu.h
snip
+/*
+ * Map a part of the scatter-gather list into contiguous io address space
+ */
+static int __map_sg_chunk(struct device *dev, struct scatterlist *sg,
+ size_t size, dma_addr_t *handle,
+ enum dma_data_direction dir)
+{
+ struct dma_iommu_mapping *mapping = dev-archdata.mapping;
+ dma_addr_t iova, iova_base;
+ int ret = 0;
+ unsigned int count;
+ struct scatterlist *s;
+
+ size = PAGE_ALIGN(size);
+ *handle = ARM_DMA_ERROR;
+
+ iova_base = iova = __alloc_iova(mapping, size);
+ if (iova == ARM_DMA_ERROR)
+ return -ENOMEM;
+
+ for (count = 0, s = sg; count (size PAGE_SHIFT); s =
sg_next(s))
+ {
+ phys_addr_t phys = page_to_phys(sg_page(s));
+ unsigned int len = PAGE_ALIGN(s-offset + s-length);
+
+ if (!arch_is_coherent())
+ __dma_page_cpu_to_dev(sg_page(s), s-offset,
s-length, dir);
+
+ ret = iommu_map(mapping-domain, iova, phys, len, 0);
+ if (ret 0)
+ goto fail;
+ count += len PAGE_SHIFT;
+ iova += len;
+ }
+ *handle = iova_base;
+
+ return 0;
+fail:
+ iommu_unmap(mapping-domain, iova_base, count * PAGE_SIZE);
+ __free_iova(mapping, iova_base, size);
+ return ret;
+}
Do we need to set dma_address as below?
Nope, this one is not correct. Please check the arm_iommu_map_sg() function. It
calls
__map_sg_chunk() and gives it dma-dma_address as one of the arguments, so the
dma
address is correctly stored in the scatter list. Please note that scatterlist
is really
non-trivial structure and information about physical memory pages/chunks is
disjoint
from the information about dma address space chunks, although both are stored
on the
same list. In arm_iommu_map_sg() 's' pointer is used for physical memory chunks
and
'dma' pointer is used for dma address space chunks.
The number of dma address space chunks (returned by arm_iommu_map_sq) can be
lower
than the number of physical memory chunks (given as nents argument).
In case of IOMMU you usually construct the scatter list in such a way, that you
get
only one dma address chunk (so in fact you get a buffer mapped contiguously in
virtual io address space).
From e8bcc3cdac5375b5d7f5ac5b3f716a11c1008f38 Mon Sep 17 00:00:00 2001
From: Hiroshi DOYU hd...@nvidia.com
Date: Thu, 29 Mar 2012 09:59:04 +0300
Subject: [PATCH 1/1] ARM: dma-mapping: Fix dma_address in sglist
s-dma_address wasn't set at mapping.
Signed-off-by: Hiroshi DOYU hd...@nvidia.com
---
arch/arm/mm/dma-mapping.c |2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 3347c37..11a9d65 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -,6 +,8 @@ static int __map_sg_chunk(struct device *dev, struct
scatterlist *sg,
ret = iommu_map(mapping-domain, iova, phys, len, 0);
if (ret 0)
goto fail;
+ s-dma_address = iova;
+
count += len PAGE_SHIFT;
iova += len;
}
The above patch is not needed at all.
Best regards
--
Marek Szyprowski
Samsung Poland RD Center
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