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Commit b67a8b29 authored by Jisheng Zhang's avatar Jisheng Zhang Committed by Catalin Marinas
Browse files

arm64: mm: only initialize swiotlb when necessary 



we only initialize swiotlb when swiotlb_force is true or not all system
memory is DMA-able, this trivial optimization saves us 64MB when
swiotlb is not necessary.

Signed-off-by: default avatarJisheng Zhang <jszhang@marvell.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 83ce0efc

arch/arm64/mm/dma-mapping.c

+14 −1
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ 


#include <linux/gfp.h>

#include <linux/acpi.h>

#include <linux/bootmem.h>

#include <linux/export.h>

#include <linux/slab.h>

#include <linux/genalloc.h>
@@ -29,6 +30,8 @@ 


#include <asm/cacheflush.h>



static int swiotlb __read_mostly;



static pgprot_t __get_dma_pgprot(struct dma_attrs *attrs, pgprot_t prot,

				 bool coherent)

{
@@ -341,6 +344,13 @@ static int __swiotlb_get_sgtable(struct device *dev, struct sg_table *sgt, 
	return ret;

}



static int __swiotlb_dma_supported(struct device *hwdev, u64 mask)

{

	if (swiotlb)

		return swiotlb_dma_supported(hwdev, mask);

	return 1;

}



static struct dma_map_ops swiotlb_dma_ops = {

	.alloc = __dma_alloc,

	.free = __dma_free,
@@ -354,7 +364,7 @@ static struct dma_map_ops swiotlb_dma_ops = { 
	.sync_single_for_device = __swiotlb_sync_single_for_device,

	.sync_sg_for_cpu = __swiotlb_sync_sg_for_cpu,

	.sync_sg_for_device = __swiotlb_sync_sg_for_device,

	.dma_supported = swiotlb_dma_supported,

	.dma_supported = __swiotlb_dma_supported,

	.mapping_error = swiotlb_dma_mapping_error,

};
@@ -513,6 +523,9 @@ EXPORT_SYMBOL(dummy_dma_ops); 


static int __init arm64_dma_init(void)

{

	if (swiotlb_force || max_pfn > (arm64_dma_phys_limit >> PAGE_SHIFT))

		swiotlb = 1;



	return atomic_pool_init();

}

arch_initcall(arm64_dma_init);

arch/arm64/mm/init.c

+2 −1
Original line number Diff line number Diff line
@@ -403,6 +403,7 @@ static void __init free_unused_memmap(void) 
 */

void __init mem_init(void)

{

	if (swiotlb_force || max_pfn > (arm64_dma_phys_limit >> PAGE_SHIFT))

		swiotlb_init(1);



	set_max_mapnr(pfn_to_page(max_pfn) - mem_map);