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* [PATCH/RFC,2/6] dma-coherent: Add NO_DMA dummies for managed DMA API
@ 2018-02-06 10:14 Geert Uytterhoeven
  0 siblings, 0 replies; only message in thread
From: Geert Uytterhoeven @ 2018-02-06 10:14 UTC (permalink / raw)
  To: Christoph Hellwig, Marek Szyprowski, Robin Murphy, Arnd Bergmann,
	Mark Brown, Richard Weinberger
  Cc: Felipe Balbi, Greg Kroah-Hartman, James E . J . Bottomley,
	Martin K . Petersen, iommu, linux-usb, linux-scsi, linux-kernel,
	linux-arch, Geert Uytterhoeven

Add dummies for dmam_{alloc,free}_coherent(), to allow compile-testing
if NO_DMA=y.

This prevents the following from showing up later:

    ERROR: "dmam_alloc_coherent" [drivers/net/ethernet/arc/arc_emac.ko] undefined!
    ERROR: "dmam_free_coherent" [drivers/net/ethernet/apm/xgene/xgene-enet.ko] undefined!
    ERROR: "dmam_alloc_coherent" [drivers/net/ethernet/apm/xgene/xgene-enet.ko] undefined!
    ERROR: "dmam_alloc_coherent" [drivers/mtd/nand/hisi504_nand.ko] undefined!
    ERROR: "dmam_alloc_coherent" [drivers/mmc/host/dw_mmc.ko] undefined!

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
 include/linux/dma-mapping.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index d78d7541f784875b..4d92956a4ddb8a5c 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -776,10 +776,19 @@ static inline void dma_deconfigure(struct device *dev) {}
 /*
  * Managed DMA API
  */
+#ifdef CONFIG_HAS_DMA
 extern void *dmam_alloc_coherent(struct device *dev, size_t size,
 				 dma_addr_t *dma_handle, gfp_t gfp);
 extern void dmam_free_coherent(struct device *dev, size_t size, void *vaddr,
 			       dma_addr_t dma_handle);
+#else /* !CONFIG_HAS_DMA */
+static inline void *dmam_alloc_coherent(struct device *dev, size_t size,
+					dma_addr_t *dma_handle, gfp_t gfp)
+{ return NULL; }
+static inline void dmam_free_coherent(struct device *dev, size_t size,
+				      void *vaddr, dma_addr_t dma_handle) { }
+#endif /* !CONFIG_HAS_DMA */
+
 extern void *dmam_alloc_attrs(struct device *dev, size_t size,
 			      dma_addr_t *dma_handle, gfp_t gfp,
 			      unsigned long attrs);

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