Commit 2d5a5612bc (arm64: Limit the CMA buffer to 32-bit if ZONE_DMA)
forces the CMA buffer to be 32-bit addressable if CONFIG_ZONE_DMA is
defined. This breaks CMA on platforms with no 32-bit addressable DRAM.
This patch checks to make sure there is 32-bit addressable DRAM before
setting the 32-bit limit. If there is none, no limit is placed on the
CMA buffer. This allows a single kernel (with CONFIG_ZONE_DMA defined)
to support platforms requiring the 32-bit limit and platforms with no
32-bit limit.
Signed-off-by: Mark Salter <msal...@redhat.com>
---
arch/arm64/mm/init.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index c5415e2..2925576 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -149,8 +149,17 @@ void __init arm64_memblock_init(void)
early_init_fdt_scan_reserved_mem();
/* 4GB maximum for 32-bit only capable devices */
- if (IS_ENABLED(CONFIG_ZONE_DMA))
+ if (IS_ENABLED(CONFIG_ZONE_DMA)) {
dma_phys_limit = dma_to_phys(NULL, DMA_BIT_MASK(32)) + 1;
+ /*
+ * If platform doesn't have DRAM within the dma_phys_limit,
+ * remove the limit altogether. This allows one kernel (with
+ * CONFIG_ZONE_DMA defined) to support platforms with 32-bit
+ * only devices and platforms with no 32-bit DRAM.
+ */
+ if (dma_phys_limit <= memblock_start_of_DRAM())
+ dma_phys_limit = 0;
+ }
dma_contiguous_reserve(dma_phys_limit);
memblock_allow_resize();
--
1.8.3.1
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