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powerpc/64: Honor swiotlb limit in coherent allocations

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FSL PCI cannot directly address the whole lower 4 GiB due to
conflicts with PCICSRBAR and outbound windows, and thus
max_direct_dma_addr is less than 4GiB.  Honor that limit in
dma_direct_alloc_coherent().

Note that setting the DMA mask to 31 bits is not an option, since many
PCI drivers would fail if we reject 32-bit DMA in dma_supported(), and
we have no control over the setting of coherent_dma_mask if
dma_supported() returns true.

Signed-off-by: Scott Wood <scottwood@freescale.com>
Cc: Shaohui Xie <Shaohui.Xie@freescale.com>
This commit is contained in:
Scott Wood 2014-08-08 18:40:43 -05:00
parent 1c98025c6c
commit 6397fc3fb0
1 changed files with 14 additions and 1 deletions
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15
arch/powerpc/kernel/dma.c
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@ -15,6 +15,7 @@
#include <asm/vio.h>
#include <asm/bug.h>
#include <asm/machdep.h>
#include <asm/swiotlb.h>
/*
* Generic direct DMA implementation
@ -25,6 +26,18 @@
* default the offset is PCI_DRAM_OFFSET.
*/
static u64 __maybe_unused get_pfn_limit(struct device *dev)
{
u64 pfn = (dev->coherent_dma_mask >> PAGE_SHIFT) + 1;
struct dev_archdata __maybe_unused *sd = &dev->archdata;
#ifdef CONFIG_SWIOTLB
if (sd->max_direct_dma_addr && sd->dma_ops == &swiotlb_dma_ops)
pfn = min_t(u64, pfn, sd->max_direct_dma_addr >> PAGE_SHIFT);
#endif
return pfn;
}
void *dma_direct_alloc_coherent(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t flag,
@ -40,7 +53,7 @@ void *dma_direct_alloc_coherent(struct device *dev, size_t size,
#else
struct page *page;
int node = dev_to_node(dev);
u64 pfn = (dev->coherent_dma_mask >> PAGE_SHIFT) + 1;
u64 pfn = get_pfn_limit(dev);
int zone;
zone = dma_pfn_limit_to_zone(pfn);