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Subject[PATCH v2 1/5] dma-mapping: Convert NO_DMA get_dma_ops() into a real dummy
Date
If NO_DMA=y, get_dma_ops() returns a reference to the
non-existing symbol bad_dma_ops, thus causing a link failure if it is
ever used.

Make get_dma_ops() return NULL instead, to avoid the link failure.
This allows to improve compile-testing, and limits the need to keep on
sprinkling dependencies on HAS_DMA all over the place.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Mark Brown <broonie@kernel.org>
Acked-by: Robin Murphy <robin.murphy@arm.com>
---
v2:
- Add Reviewed-by, Acked-by,
- Drop RFC state.
---
include/linux/dma-mapping.h | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index eb9eab4ecd6d7a05..5ea7eec83c0fbb82 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -212,14 +212,14 @@ static inline void set_dma_ops(struct device *dev,
}
#else
/*
- * Define the dma api to allow compilation but not linking of
- * dma dependent code. Code that depends on the dma-mapping
- * API needs to set 'depends on HAS_DMA' in its Kconfig
+ * Define the dma api to allow compilation of dma dependent code.
+ * Code that depends on the dma-mapping API needs to set 'depends on HAS_DMA'
+ * in its Kconfig, unless it already depends on <something> || COMPILE_TEST,
+ * where <something> guarantuees the availability of the dma-mapping API.
*/
-extern const struct dma_map_ops bad_dma_ops;
static inline const struct dma_map_ops *get_dma_ops(struct device *dev)
{
- return &bad_dma_ops;
+ return NULL;
}
#endif

--
2.7.4
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