MIPS: improve checks for noncoherent DMA

Only one MIPS development board actually supports enabling/disabling DMA
coherency at runtime, so it's not a good idea to push the overhead of
checking that configuration setting onto every other supported target as
well.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John Crispin <blogic@openwrt.org>
Patchwork: http://patchwork.linux-mips.org/patch/5912/

2 files changed, 9 insertions, 4 deletions

diff --git a/arch/mips/include/asm/dma-coherence.h b/arch/mips/include/asm/dma-coherence.h
index 242cbb3ca582..bc5e85d579e6 100644
--- a/arch/mips/include/asm/dma-coherence.h
+++ b/arch/mips/include/asm/dma-coherence.h
@@ -9,7 +9,16 @@
 #ifndef __ASM_DMA_COHERENCE_H
 #define __ASM_DMA_COHERENCE_H
 
+#ifdef CONFIG_DMA_MAYBE_COHERENT
 extern int coherentio;
 extern int hw_coherentio;
+#else
+#ifdef CONFIG_DMA_COHERENT
+#define coherentio      1
+#else
+#define coherentio      0
+#endif
+#define hw_coherentio   0
+#endif /* CONFIG_DMA_MAYBE_COHERENT */
 
 #endif
diff --git a/arch/mips/include/asm/mach-generic/dma-coherence.h b/arch/mips/include/asm/mach-generic/dma-coherence.h
index a9e8f6b62b0b..7629c35986f7 100644
--- a/arch/mips/include/asm/mach-generic/dma-coherence.h
+++ b/arch/mips/include/asm/mach-generic/dma-coherence.h
@@ -49,11 +49,7 @@ static inline int plat_dma_supported(struct device *dev, u64 mask)
 
 static inline int plat_device_is_coherent(struct device *dev)
 {
-#ifdef CONFIG_DMA_COHERENT
-        return 1;
-#else
         return coherentio;
-#endif
 }
 
 #ifdef CONFIG_SWIOTLB