On Aug 24, 2012, at 5:50 AM, Shaohui Xie wrote:
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.
=20
So we split the memory to two zones: zone ZONE_DMA32 & 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_DMA32
to 2GB, also, we clear flag __GFP_DMA & __GFP_DMA32 and set =
__GFP_DMA32 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_DMA32, but devices =
which
can DMA all the memory will not be affected by this limitation.
=20
Signed-off-by: Shaohui Xie <redacted>
Signed-off-by: Mingkai Hu <redacted>
Signed-off-by: Chen Yuanquan <redacted>
---
changes for v2:
1. use a config option for using two zones (ZONE_DMA32 & ZONE_NORMAL) =
in
freescale 64 bit kernel.
=20
arch/powerpc/Kconfig | 3 +++
arch/powerpc/kernel/dma.c | 15 +++++++++++++++
arch/powerpc/mm/mem.c | 4 ++++
3 files changed, 22 insertions(+), 0 deletions(-)
Ben,
What's the feeling of doing this on ppc64 always?=20
- k
quoted hunk
=20
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 352f416..a96fbbb 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -629,6 +629,9 @@ config ZONE_DMA
bool
default y
=20
+config ZONE_DMA32
+ def_bool (PPC64 && PPC_FSL_BOOK3E)
+
config NEED_DMA_MAP_STATE
def_bool (PPC64 || NOT_COHERENT_CACHE)
=20
diff --git a/arch/powerpc/kernel/dma.c b/arch/powerpc/kernel/dma.c
index 355b9d8..cbf5ac1 100644
--- a/arch/powerpc/kernel/dma.c
+++ b/arch/powerpc/kernel/dma.c
@@ -41,9 +41,24 @@ void *dma_direct_alloc_coherent(struct device *dev, =
size_t size,
#else
struct page *page;
int node =3D dev_to_node(dev);
+#ifdef CONFIG_ZONE_DMA32
+ phys_addr_t top_ram_pfn =3D memblock_end_of_DRAM();
=20
+ /*
+ * 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);
quoted hunk
+ return NULL;
+ }
/* ignore region specifiers */
+ flag &=3D ~(__GFP_HIGHMEM | __GFP_DMA | __GFP_DMA32);
+ if (*dev->dma_mask < top_ram_pfn - 1)
+ flag |=3D __GFP_DMA32;
+#else
flag &=3D ~(__GFP_HIGHMEM);
+#endif
=20
page =3D alloc_pages_node(node, flag, get_order(size));
if (page =3D=3D NULL)
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index baaafde..2a11e49 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -280,6 +280,10 @@ void __init paging_init(void)
#ifdef CONFIG_HIGHMEM
max_zone_pfns[ZONE_DMA] =3D lowmem_end_addr >> PAGE_SHIFT;
max_zone_pfns[ZONE_HIGHMEM] =3D top_of_ram >> PAGE_SHIFT;
+#elif defined CONFIG_ZONE_DMA32
+ max_zone_pfns[ZONE_DMA32] =3D min_t(phys_addr_t, top_of_ram,
+ 1ull << 31) >> PAGE_SHIFT;
+ max_zone_pfns[ZONE_NORMAL] =3D top_of_ram >> PAGE_SHIFT;
#else
max_zone_pfns[ZONE_DMA] =3D top_of_ram >> PAGE_SHIFT;
#endif
--=20
1.6.4
=20
=20
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