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Commit a492dbb9 authored by Haavard Skinnemoen's avatar Haavard Skinnemoen
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[AVR32] Implement dma_{alloc,free}_writecombine() 



Implement dma_alloc_writecombine() and its dma_free_writecombine()
counterpart. These will do basically the same thing as
dma_alloc_coherent() except that the virtual mapping will allow
write buffering, causing better performance for certain use cases
like frame buffers.

The same API is already available on ARM.

Signed-off-by: default avatarHaavard Skinnemoen <hskinnemoen@atmel.com>
parent e89b064a

arch/avr32/mm/dma-coherent.c

+8 −4
Original line number Diff line number Diff line
@@ -112,16 +112,21 @@ void dma_free_coherent(struct device *dev, size_t size, 
}

EXPORT_SYMBOL(dma_free_coherent);



#if 0

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

			     dma_addr_t *handle, gfp_t gfp)

{

	struct page *page;

	dma_addr_t phys;



	page = __dma_alloc(dev, size, handle, gfp);

	if (!page)

		return NULL;



	phys = page_to_phys(page);

	*handle = phys;



	/* Now, map the page into P3 with write-combining turned on */

	return __ioremap(page_to_phys(page), size, _PAGE_BUFFER);

	return __ioremap(phys, size, _PAGE_BUFFER);

}

EXPORT_SYMBOL(dma_alloc_writecombine);
@@ -132,8 +137,7 @@ void dma_free_writecombine(struct device *dev, size_t size, 


	iounmap(cpu_addr);



	page = bus_to_page(handle);

	page = phys_to_page(handle);

	__dma_free(dev, size, page, handle);

}

EXPORT_SYMBOL(dma_free_writecombine);
 
#endif