Commit 55af8a91 authored by Mike Looijmans's avatar Mike Looijmans Committed by Russell King
Browse files

ARM: 8387/1: arm/mm/dma-mapping.c: Add arm_coherent_dma_mmap 



When dma-coherent transfers are enabled, the mmap call must
not change the pg_prot flags in the vma struct.

Split the arm_dma_mmap into a common and specific parts,
and add a "arm_coherent_dma_mmap" implementation that does
not alter the page protection flags.

Tested on a topic-miami board (Zynq) using the ACP port
to transfer data between FPGA and CPU using the Dyplo
framework. Without this patch, byte-wise access to mmapped
coherent DMA memory was about 20x slower because of the
memory being marked as non-cacheable, and transfer speeds
would not exceed 240MB/s.

After this patch, the mapped memory is cacheable and the
transfer speed is again 600MB/s (limited by the FPGA) when
the data is in the L2 cache, while data integrity is being
maintained.

The patch has no effect on non-coherent DMA.

Signed-off-by: default avatarMike Looijmans <mike.looijmans@topic.nl>
Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent e001bbae

arch/arm/mm/dma-mapping.c

+25 −7
Original line number Diff line number Diff line
@@ -148,11 +148,14 @@ static void *arm_coherent_dma_alloc(struct device *dev, size_t size, 
	dma_addr_t *handle, gfp_t gfp, struct dma_attrs *attrs);

static void arm_coherent_dma_free(struct device *dev, size_t size, void *cpu_addr,

				  dma_addr_t handle, struct dma_attrs *attrs);

static int arm_coherent_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);



struct dma_map_ops arm_coherent_dma_ops = {

	.alloc			= arm_coherent_dma_alloc,

	.free			= arm_coherent_dma_free,

	.mmap			= arm_dma_mmap,

	.mmap			= arm_coherent_dma_mmap,

	.get_sgtable		= arm_dma_get_sgtable,

	.map_page		= arm_coherent_dma_map_page,

	.map_sg			= arm_dma_map_sg,
@@ -690,10 +693,7 @@ static void *arm_coherent_dma_alloc(struct device *dev, size_t size, 
			   attrs, __builtin_return_address(0));

}



/*

 * Create userspace mapping for the DMA-coherent memory.

 */

int arm_dma_mmap(struct device *dev, struct vm_area_struct *vma,

static 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)

{
@@ -704,8 +704,6 @@ int arm_dma_mmap(struct device *dev, struct vm_area_struct *vma, 
	unsigned long pfn = dma_to_pfn(dev, dma_addr);

	unsigned long off = vma->vm_pgoff;



	vma->vm_page_prot = __get_dma_pgprot(attrs, vma->vm_page_prot);



	if (dma_mmap_from_coherent(dev, vma, cpu_addr, size, &ret))

		return ret;
@@ -720,6 +718,26 @@ int arm_dma_mmap(struct device *dev, struct vm_area_struct *vma, 
	return ret;

}



/*

 * Create userspace mapping for the DMA-coherent memory.

 */

static int arm_coherent_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)

{

	return __arm_dma_mmap(dev, vma, cpu_addr, dma_addr, size, attrs);

}



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)

{

#ifdef CONFIG_MMU

	vma->vm_page_prot = __get_dma_pgprot(attrs, vma->vm_page_prot);

#endif	/* CONFIG_MMU */

	return __arm_dma_mmap(dev, vma, cpu_addr, dma_addr, size, attrs);

}



/*

 * Free a buffer as defined by the above mapping.

 */

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