[PATCH 3/4] powerpc/64: Limit ZONE_DMA32 to 4GiB in swiotlb_detect_4g()

[Scott Wood]

A DMA zone is still needed with swiotlb, for coherent allocations.
This doesn't affect platforms that don't use swiotlb or that don't call
swiotlb_detect_4g().

Signed-off-by: Scott Wood <scottwood at freescale.com>
Cc: Shaohui Xie <Shaohui.Xie at freescale.com>
---
 arch/powerpc/kernel/dma-swiotlb.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/dma-swiotlb.c b/arch/powerpc/kernel/dma-swiotlb.c
index bd1a2ab..7359797 100644
--- a/arch/powerpc/kernel/dma-swiotlb.c
+++ b/arch/powerpc/kernel/dma-swiotlb.c
@@ -106,10 +106,14 @@ int __init swiotlb_setup_bus_notifier(void)
 	return 0;
 }
 
-void swiotlb_detect_4g(void)
+void __init swiotlb_detect_4g(void)
 {
-	if ((memblock_end_of_DRAM() - 1) > 0xffffffff)
+	if ((memblock_end_of_DRAM() - 1) > 0xffffffff) {
 		ppc_swiotlb_enable = 1;
+#ifdef CONFIG_ZONE_DMA32
+		limit_zone_pfn(ZONE_DMA32, (1ULL << 32) >> PAGE_SHIFT);
+#endif
+	}
 }
 
 static int __init swiotlb_late_init(void)
-- 
1.9.1