PowerPC platform only supports ZONE_DMA zone for 64bit kernel, so all the
memory will be put into this zone. If the memory size is greater than
the device's DMA capability and device uses dma_alloc_coherent to allocate
memory, it will get an address which is over the device's DMA addressing,
the device will fail.
So we split the memory to two zones by adding a zone ZONE_NORMAL, since
we already allocate PCICSRBAR/PEXCSRBAR right below the 4G boundary (if the
lowest PCI address is above 4G), so we constrain the DMA zone ZONE_DMA
to 2GB, also, we clear the flag __GFP_DMA and set it only if the device's
dma_mask < total memory size. By doing this, devices which cannot DMA all
the memory will be limited to ZONE_DMA, but devices which can DMA all the
memory will not be affected by this limitation.
Signed-off-by: Shaohui Xie <shaohui....@freescale.com>
Signed-off-by: Mingkai Hu <mingkai...@freescale.com>
Signed-off-by: Chen Yuanquan <b41...@freescale.com>
---
arch/powerpc/kernel/dma.c | 13 ++++++++++++-
arch/powerpc/mm/mem.c | 4 +++-
2 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kernel/dma.c b/arch/powerpc/kernel/dma.c
index b1ec983..8029295 100644
--- a/arch/powerpc/kernel/dma.c
+++ b/arch/powerpc/kernel/dma.c
@@ -30,6 +30,7 @@ void *dma_direct_alloc_coherent(struct device *dev, size_t
size,
struct dma_attrs *attrs)
{
void *ret;
+ phys_addr_t top_ram_pfn = memblock_end_of_DRAM();
#ifdef CONFIG_NOT_COHERENT_CACHE
ret = __dma_alloc_coherent(dev, size, dma_handle, flag);
if (ret == NULL)
@@ -40,8 +41,18 @@ void *dma_direct_alloc_coherent(struct device *dev, size_t
size,
struct page *page;
int node = dev_to_node(dev);
+ /*
+ * check for crappy device which has dma_mask < ZONE_DMA, and
+ * we are not going to support it, just warn and fail.
+ */
+ if (*dev->dma_mask < DMA_BIT_MASK(31)) {
+ dev_err(dev, "Unsupported dma_mask 0x%llx\n", *dev->dma_mask);
+ return NULL;
+ }
/* ignore region specifiers */
- flag &= ~(__GFP_HIGHMEM);
+ flag &= ~(__GFP_HIGHMEM | __GFP_DMA);
+ if (*dev->dma_mask < top_ram_pfn - 1)
+ flag |= GFP_DMA;
page = alloc_pages_node(node, flag, get_order(size));
if (page == NULL)
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index baaafde..a494555 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -281,7 +281,9 @@ void __init paging_init(void)
max_zone_pfns[ZONE_DMA] = lowmem_end_addr >> PAGE_SHIFT;
max_zone_pfns[ZONE_HIGHMEM] = top_of_ram >> PAGE_SHIFT;
#else
- max_zone_pfns[ZONE_DMA] = top_of_ram >> PAGE_SHIFT;
+ max_zone_pfns[ZONE_DMA] = min_t(phys_addr_t, top_of_ram,
+ 1ull << 31) >> PAGE_SHIFT;
+ max_zone_pfns[ZONE_NORMAL] = top_of_ram >> PAGE_SHIFT;
#endif
free_area_init_nodes(max_zone_pfns);
--
1.6.4
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