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Commit dff8d6c1 authored by Christoph Hellwig's avatar Christoph Hellwig
Browse files

swiotlb: remove the overflow buffer 



Like all other dma mapping drivers just return an error code instead
of an actual memory buffer.  The reason for the overflow buffer was
that at the time swiotlb was invented there was no way to check for
dma mapping errors, but this has long been fixed.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Reviewed-by: default avatarRobin Murphy <robin.murphy@arm.com>
Reviewed-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
parent 80885468

arch/arm64/mm/dma-mapping.c

+1 −1
Original line number Diff line number Diff line
@@ -324,7 +324,7 @@ static int __swiotlb_dma_supported(struct device *hwdev, u64 mask) 
static int __swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t addr)

{

	if (swiotlb)

		return swiotlb_dma_mapping_error(hwdev, addr);

		return dma_direct_mapping_error(hwdev, addr);

	return 0;

}

arch/powerpc/kernel/dma-swiotlb.c

+2 −2
Original line number Diff line number Diff line
@@ -11,7 +11,7 @@ 
 *

 */



#include <linux/dma-mapping.h>

#include <linux/dma-direct.h>

#include <linux/memblock.h>

#include <linux/pfn.h>

#include <linux/of_platform.h>
@@ -59,7 +59,7 @@ const struct dma_map_ops powerpc_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,

	.mapping_error = swiotlb_dma_mapping_error,

	.mapping_error = dma_direct_mapping_error,

	.get_required_mask = swiotlb_powerpc_get_required,

};

include/linux/dma-direct.h

+2 −0
Original line number Diff line number Diff line
@@ -5,6 +5,8 @@ 
#include <linux/dma-mapping.h>

#include <linux/mem_encrypt.h>



#define DIRECT_MAPPING_ERROR		0



#ifdef CONFIG_ARCH_HAS_PHYS_TO_DMA

#include <asm/dma-direct.h>

#else

include/linux/swiotlb.h

+0 −3
Original line number Diff line number Diff line
@@ -106,9 +106,6 @@ extern void 
swiotlb_sync_sg_for_device(struct device *hwdev, struct scatterlist *sg,

			   int nelems, enum dma_data_direction dir);



extern int

swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t dma_addr);



extern int

swiotlb_dma_supported(struct device *hwdev, u64 mask);

kernel/dma/direct.c

+0 −2
Original line number Diff line number Diff line
@@ -14,8 +14,6 @@ 
#include <linux/pfn.h>

#include <linux/set_memory.h>



#define DIRECT_MAPPING_ERROR		0



/*

 * Most architectures use ZONE_DMA for the first 16 Megabytes, but

 * some use it for entirely different regions: