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authorNicolas Saenz Julienne <nsaenzjulienne@suse.de>2019-10-14 20:31:03 +0200
committerCatalin Marinas <catalin.marinas@arm.com>2019-11-01 09:41:18 +0000
commit8b5369ea580964dbc982781bfb9fb93459fc5e8d (patch)
tree55f4d7308e5fb1f4c5df396e637ba08bfa2daf46 /kernel/dma
parent4686da5140c18c84ca01a8ab994571d832c63398 (diff)
dma/direct: turn ARCH_ZONE_DMA_BITS into a variable
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>
Diffstat (limited to 'kernel/dma')
-rw-r--r--kernel/dma/direct.c13
1 files changed, 6 insertions, 7 deletions
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 8402b29c280f..0b67c04e531b 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -16,12 +16,11 @@
#include <linux/swiotlb.h>
/*
- * Most architectures use ZONE_DMA for the first 16 Megabytes, but
- * some use it for entirely different regions:
+ * Most architectures use ZONE_DMA for the first 16 Megabytes, but some use it
+ * it for entirely different regions. In that case the arch code needs to
+ * override the variable below for dma-direct to work properly.
*/
-#ifndef ARCH_ZONE_DMA_BITS
-#define ARCH_ZONE_DMA_BITS 24
-#endif
+unsigned int zone_dma_bits __ro_after_init = 24;
static void report_addr(struct device *dev, dma_addr_t dma_addr, size_t size)
{
@@ -69,7 +68,7 @@ static gfp_t __dma_direct_optimal_gfp_mask(struct device *dev, u64 dma_mask,
* Note that GFP_DMA32 and GFP_DMA are no ops without the corresponding
* zones.
*/
- if (*phys_mask <= DMA_BIT_MASK(ARCH_ZONE_DMA_BITS))
+ if (*phys_mask <= DMA_BIT_MASK(zone_dma_bits))
return GFP_DMA;
if (*phys_mask <= DMA_BIT_MASK(32))
return GFP_DMA32;
@@ -395,7 +394,7 @@ int dma_direct_supported(struct device *dev, u64 mask)
u64 min_mask;
if (IS_ENABLED(CONFIG_ZONE_DMA))
- min_mask = DMA_BIT_MASK(ARCH_ZONE_DMA_BITS);
+ min_mask = DMA_BIT_MASK(zone_dma_bits);
else
min_mask = DMA_BIT_MASK(32);