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arm64: mm: only initialize swiotlb when necessary

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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: Jisheng Zhang <jszhang@marvell.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Jisheng Zhang 2016-06-08 15:53:46 +08:00 committed by Catalin Marinas
parent 83ce0efc12
commit b67a8b29df
2 changed files with 16 additions and 2 deletions
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15
arch/arm64/mm/dma-mapping.c
View File

@ -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);

3
arch/arm64/mm/init.c
View File

@ -403,7 +403,8 @@ static void __init free_unused_memmap(void)
*/
void __init mem_init(void)
{
swiotlb_init(1);
if (swiotlb_force || max_pfn > (arm64_dma_phys_limit >> PAGE_SHIFT))
swiotlb_init(1);
set_max_mapnr(pfn_to_page(max_pfn) - mem_map);