[PATCH 1/1] drivers: of: of_reserved_mem: fixup the alignment with CMA setup

Jason Liu r64343 at freescale.com
Tue Nov 10 04:30:26 PST 2015

There is an alignment mismatch issue between the of_reserved_mem and
the CMA setup requirement. The of_reserved_mem will try to get the
alignment value from the DTS and pass it to __memblock_alloc_base to
do the memory block base allocation, but the alignment value specified
in the DTS may not satisfy the CAM setup requirement since CMA setup
required the alignment as the following in the code:

align = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order);

The sanity check in the function of rmem_cma_setup will fail if the
alignment does not setup correctly and thus CMA will fail to setup.

This patch is to fixup the alignment to meet the CMA setup required.

Mailing-list-thread: https://lkml.org/lkml/2015/11/9/138
Signed-off-by: Jason Liu <r64343 at freescale.com>
Cc: Marek Szyprowski <m.szyprowski at samsung.com>
Cc: Grant Likely <grant.likely at linaro.org>
Cc: Rob Herring <robh+dt at kernel.org>
 drivers/of/of_reserved_mem.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
index 62f467b..9394311 100644
--- a/drivers/of/of_reserved_mem.c
+++ b/drivers/of/of_reserved_mem.c
@@ -124,6 +124,10 @@ static int __init __reserved_mem_alloc_size(unsigned long node,
 		align = dt_mem_next_cell(dt_root_addr_cells, &prop);
+	/* Need adjust the alignment to satisfy the CMA requirement */
+	if (IS_ENABLED(CONFIG_CMA) && of_flat_dt_is_compatible(node, "shared-dma-pool"))
+		align = max(align, (phys_addr_t)PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order));
 	prop = of_get_flat_dt_prop(node, "alloc-ranges", &len);
 	if (prop) {

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