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dma/direct: turn ARCH_ZONE_DMA_BITS into a variable

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Some architectures, notably ARM, are interested in tweaking this
depending on their runtime DMA addressing limitations.

Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Nicolas Saenz Julienne
2019-10-14 20:31:03 +02:00
committed by Catalin Marinas
parent 4686da5140
commit 8b5369ea58
8 changed files with 31 additions and 27 deletions
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20
arch/powerpc/mm/mem.c
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@@ -31,6 +31,7 @@
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/memremap.h>
#include <linux/dma-direct.h>
#include <asm/pgalloc.h>
#include <asm/prom.h>
@@ -201,10 +202,10 @@ static int __init mark_nonram_nosave(void)
* everything else. GFP_DMA32 page allocations automatically fall back to
* ZONE_DMA.
*
* By using 31-bit unconditionally, we can exploit ARCH_ZONE_DMA_BITS to
* inform the generic DMA mapping code. 32-bit only devices (if not handled
* by an IOMMU anyway) will take a first dip into ZONE_NORMAL and get
* otherwise served by ZONE_DMA.
* By using 31-bit unconditionally, we can exploit zone_dma_bits to inform the
* generic DMA mapping code. 32-bit only devices (if not handled by an IOMMU
* anyway) will take a first dip into ZONE_NORMAL and get otherwise served by
* ZONE_DMA.
*/
static unsigned long max_zone_pfns[MAX_NR_ZONES];
@@ -237,9 +238,18 @@ void __init paging_init(void)
printk(KERN_DEBUG "Memory hole size: %ldMB\n",
(long int)((top_of_ram - total_ram) >> 20));
/*
* Allow 30-bit DMA for very limited Broadcom wifi chips on many
* powerbooks.
*/
if (IS_ENABLED(CONFIG_PPC32))
zone_dma_bits = 30;
else
zone_dma_bits = 31;
#ifdef CONFIG_ZONE_DMA
max_zone_pfns[ZONE_DMA] = min(max_low_pfn,
1UL << (ARCH_ZONE_DMA_BITS - PAGE_SHIFT));
1UL << (zone_dma_bits - PAGE_SHIFT));
#endif
max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
#ifdef CONFIG_HIGHMEM