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Commit 6f51f515 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'for-linus-for-3.6-rc1' of git://git.linaro.org/people/mszyprowski/linux-dma-mapping 

Pull DMA-mapping updates from Marek Szyprowski:
 "Those patches are continuation of my earlier work.

  They contains extensions to DMA-mapping framework to remove limitation
  of the current ARM implementation (like limited total size of DMA
  coherent/write combine buffers), improve performance of buffer sharing
  between devices (attributes to skip cpu cache operations or creation
  of additional kernel mapping for some specific use cases) as well as
  some unification of the common code for dma_mmap_attrs() and
  dma_mmap_coherent() functions.  All extensions have been implemented
  and tested for ARM architecture."

* 'for-linus-for-3.6-rc1' of git://git.linaro.org/people/mszyprowski/linux-dma-mapping:
  ARM: dma-mapping: add support for DMA_ATTR_SKIP_CPU_SYNC attribute
  common: DMA-mapping: add DMA_ATTR_SKIP_CPU_SYNC attribute
  ARM: dma-mapping: add support for dma_get_sgtable()
  common: dma-mapping: introduce dma_get_sgtable() function
  ARM: dma-mapping: add support for DMA_ATTR_NO_KERNEL_MAPPING attribute
  common: DMA-mapping: add DMA_ATTR_NO_KERNEL_MAPPING attribute
  common: dma-mapping: add support for generic dma_mmap_* calls
  ARM: dma-mapping: fix error path for memory allocation failure
  ARM: dma-mapping: add more sanity checks in arm_dma_mmap()
  ARM: dma-mapping: remove custom consistent dma region
  mm: vmalloc: use const void * for caller argument
  scatterlist: add sg_alloc_table_from_pages function
parents 76159c20 97ef952a

Documentation/DMA-attributes.txt

+42 −0
Original line number Diff line number Diff line
@@ -49,3 +49,45 @@ DMA_ATTR_NON_CONSISTENT lets the platform to choose to return either 
consistent or non-consistent memory as it sees fit.  By using this API,

you are guaranteeing to the platform that you have all the correct and

necessary sync points for this memory in the driver.



DMA_ATTR_NO_KERNEL_MAPPING

--------------------------



DMA_ATTR_NO_KERNEL_MAPPING lets the platform to avoid creating a kernel

virtual mapping for the allocated buffer. On some architectures creating

such mapping is non-trivial task and consumes very limited resources

(like kernel virtual address space or dma consistent address space).

Buffers allocated with this attribute can be only passed to user space

by calling dma_mmap_attrs(). By using this API, you are guaranteeing

that you won't dereference the pointer returned by dma_alloc_attr(). You

can threat it as a cookie that must be passed to dma_mmap_attrs() and

dma_free_attrs(). Make sure that both of these also get this attribute

set on each call.



Since it is optional for platforms to implement

DMA_ATTR_NO_KERNEL_MAPPING, those that do not will simply ignore the

attribute and exhibit default behavior.



DMA_ATTR_SKIP_CPU_SYNC

----------------------



By default dma_map_{single,page,sg} functions family transfer a given

buffer from CPU domain to device domain. Some advanced use cases might

require sharing a buffer between more than one device. This requires

having a mapping created separately for each device and is usually

performed by calling dma_map_{single,page,sg} function more than once

for the given buffer with device pointer to each device taking part in

the buffer sharing. The first call transfers a buffer from 'CPU' domain

to 'device' domain, what synchronizes CPU caches for the given region

(usually it means that the cache has been flushed or invalidated

depending on the dma direction). However, next calls to

dma_map_{single,page,sg}() for other devices will perform exactly the

same sychronization operation on the CPU cache. CPU cache sychronization

might be a time consuming operation, especially if the buffers are

large, so it is highly recommended to avoid it if possible.

DMA_ATTR_SKIP_CPU_SYNC allows platform code to skip synchronization of

the CPU cache for the given buffer assuming that it has been already

transferred to 'device' domain. This attribute can be also used for

dma_unmap_{single,page,sg} functions family to force buffer to stay in

device domain after releasing a mapping for it. Use this attribute with

care!

Documentation/kernel-parameters.txt

+1 −1
Original line number Diff line number Diff line
@@ -526,7 +526,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted. 


	coherent_pool=nn[KMG]	[ARM,KNL]

			Sets the size of memory pool for coherent, atomic dma

			allocations if Contiguous Memory Allocator (CMA) is used.

			allocations, by default set to 256K.



	code_bytes	[X86] How many bytes of object code to print

			in an oops report.

arch/arm/common/dmabounce.c

+1 −0
Original line number Diff line number Diff line
@@ -452,6 +452,7 @@ static struct dma_map_ops dmabounce_ops = { 
	.alloc			= arm_dma_alloc,

	.free			= arm_dma_free,

	.mmap			= arm_dma_mmap,

	.get_sgtable		= arm_dma_get_sgtable,

	.map_page		= dmabounce_map_page,

	.unmap_page		= dmabounce_unmap_page,

	.sync_single_for_cpu	= dmabounce_sync_for_cpu,

arch/arm/include/asm/dma-mapping.h

+4 −20
Original line number Diff line number Diff line
@@ -186,17 +186,6 @@ extern int arm_dma_mmap(struct device *dev, struct vm_area_struct *vma, 
			void *cpu_addr, dma_addr_t dma_addr, size_t size,

			struct dma_attrs *attrs);



#define dma_mmap_coherent(d, v, c, h, s) dma_mmap_attrs(d, v, c, h, s, NULL)



static inline int dma_mmap_attrs(struct device *dev, struct vm_area_struct *vma,

				  void *cpu_addr, dma_addr_t dma_addr,

				  size_t size, struct dma_attrs *attrs)

{

	struct dma_map_ops *ops = get_dma_ops(dev);

	BUG_ON(!ops);

	return ops->mmap(dev, vma, cpu_addr, dma_addr, size, attrs);

}



static inline void *dma_alloc_writecombine(struct device *dev, size_t size,

				       dma_addr_t *dma_handle, gfp_t flag)

{
@@ -213,20 +202,12 @@ static inline void dma_free_writecombine(struct device *dev, size_t size, 
	return dma_free_attrs(dev, size, cpu_addr, dma_handle, &attrs);

}



static inline int dma_mmap_writecombine(struct device *dev, struct vm_area_struct *vma,

		      void *cpu_addr, dma_addr_t dma_addr, size_t size)

{

	DEFINE_DMA_ATTRS(attrs);

	dma_set_attr(DMA_ATTR_WRITE_COMBINE, &attrs);

	return dma_mmap_attrs(dev, vma, cpu_addr, dma_addr, size, &attrs);

}



/*

 * This can be called during boot to increase the size of the consistent

 * DMA region above it's default value of 2MB. It must be called before the

 * memory allocator is initialised, i.e. before any core_initcall.

 */

extern void __init init_consistent_dma_size(unsigned long size);

static inline void init_consistent_dma_size(unsigned long size) { }



/*

 * For SA-1111, IXP425, and ADI systems  the dma-mapping functions are "magic"
@@ -280,6 +261,9 @@ extern void arm_dma_sync_sg_for_cpu(struct device *, struct scatterlist *, int, 
		enum dma_data_direction);

extern void arm_dma_sync_sg_for_device(struct device *, struct scatterlist *, int,

		enum dma_data_direction);

extern int arm_dma_get_sgtable(struct device *dev, struct sg_table *sgt,

		void *cpu_addr, dma_addr_t dma_addr, size_t size,

		struct dma_attrs *attrs);



#endif /* __KERNEL__ */

#endif

arch/arm/mm/dma-mapping.c

+227 −334

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