Hello,
On Wednesday, January 25, 2012 1:59 PM Russell King - ARM Linux wrote:
On Mon, Jan 09, 2012 at 04:49:21PM +0100, Marek Szyprowski 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 vdumpa@nvidia.com and Andrzej Pietrasiewicz andrzej.p@samsung.com
Signed-off-by: Marek Szyprowski m.szyprowski@samsung.com Signed-off-by: Kyungmin Park kyungmin.park@samsung.com
Hello,
This is the corrected version of the previous patch from the "[PATCH 0/8 v4] ARM: DMA-mapping framework redesign" thread which can be found here: http://www.spinics.net/lists/linux-mm/msg27382.html
Previous version had very nasty bug which causes memory trashing if DMA-mapping managed to allocate pages larger than 4KiB. The problem was in __iommu_alloc_buffer() function which did not check how many pages has been left to allocate.
This patch seems to be incomplete.
If the standard DMA API is used (the one which exists in current kernels) and NEED_SG_DMA_LENGTH is enabled, then where do we set the DMA length in the scatterlist?
Standard DMA API is also updated to work correctly with NEED_SG_DMA_LENGTH, please notice the following chunk:
----- @@ -644,6 +659,9 @@ int arm_dma_map_sg(struct device *dev, struct scatterlist *sg, int nents, int i, j;
for_each_sg(sg, s, nents, i) { +#ifdef CONFIG_NEED_SG_DMA_LENGTH + s->dma_length = s->length; +#endif s->dma_address = ops->map_page(dev, sg_page(s), s->offset, s->length, dir, attrs); if (dma_mapping_error(dev, s->dma_address)) ----- (http://www.spinics.net/lists/arm-kernel/msg154889.html for the reference)
diff --git a/arch/arm/include/asm/dma-iommu.h b/arch/arm/include/asm/dma-iommu.h new file mode 100644 index 0000000..6668b41 --- /dev/null +++ b/arch/arm/include/asm/dma-iommu.h @@ -0,0 +1,36 @@ +#ifndef ASMARM_DMA_IOMMU_H +#define ASMARM_DMA_IOMMU_H
+#ifdef __KERNEL__
+#include <linux/mm_types.h> +#include <linux/scatterlist.h> +#include <linux/dma-debug.h> +#include <linux/kmemcheck.h>
+#include <asm/memory.h>
I can't see anything in here which needs asm/memory.h - if files which include this need it, please include it in there so we can see why it's needed.
Ok, I will fix this issue.
+struct dma_iommu_mapping {
- /* iommu specific data */
- struct iommu_domain *domain;
- void *bitmap;
- size_t bits;
- unsigned int order;
- dma_addr_t base;
- spinlock_t lock;
- struct kref kref;
+};
+struct dma_iommu_mapping * +arm_iommu_create_mapping(struct bus_type *bus, dma_addr_t base, size_t size,
int order);+void arm_iommu_release_mapping(struct dma_iommu_mapping *mapping);
+int arm_iommu_attach_device(struct device *dev,
struct dma_iommu_mapping *mapping);+#endif /* __KERNEL__ */ +#endif diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index 4845c09..2287b01 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -27,6 +27,9 @@ #include <asm/sizes.h> #include <asm/mach/arch.h>
+#include <linux/iommu.h>
linux/ includes should be grouped together.
Ok, I will fix this.
diff --git a/arch/arm/mm/vmregion.h b/arch/arm/mm/vmregion.h index 15e9f04..6bbc402 100644 --- a/arch/arm/mm/vmregion.h +++ b/arch/arm/mm/vmregion.h @@ -17,7 +17,7 @@ struct arm_vmregion { struct list_head vm_list; unsigned long vm_start; unsigned long vm_end;
- struct page *vm_pages;
- void *priv;
I want to think about that - I may wish to export the vm_pages via the new dma-mappings file to provide additional information.
For IOMMU case I need to store a page array for each allocated buffer.
I haven't analyzed it yet, but maybe it would be possible to use standard vmalloc style entries and avoid creating separate arm_vmregion for coherent allocations?
Best regards