2 files changed, 12 insertions, 4 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 720206f46d04..d57ddd7573cc 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -123,7 +123,7 @@ config NEED_SG_DMA_LENGTH
         def_bool y
 
 config GENERIC_ISA_DMA
-        def_bool y
+        def_bool ISA_DMA_API
 
 config GENERIC_IOMAP
         def_bool y
@@ -2002,9 +2002,13 @@ source "drivers/pci/pcie/Kconfig"
 
 source "drivers/pci/Kconfig"
 
-# x86_64 have no ISA slots, but do have ISA-style DMA.
+# x86_64 have no ISA slots, but can have ISA-style DMA.
 config ISA_DMA_API
-        def_bool y
+        bool "ISA-style DMA support" if (X86_64 && EXPERT)
+        default y
+        help
+          Enables ISA-style DMA support for devices requiring such controllers.
+          If unsure, say Y.
 
 if X86_32
 
diff --git a/arch/x86/include/asm/dma.h b/arch/x86/include/asm/dma.h
index ca1098a7e580..97b6d8114a43 100644
--- a/arch/x86/include/asm/dma.h
+++ b/arch/x86/include/asm/dma.h
@@ -151,6 +151,7 @@
 #define DMA_AUTOINIT            0x10
 
 
+#ifdef CONFIG_ISA_DMA_API
 extern spinlock_t  dma_spin_lock;
 
 static inline unsigned long claim_dma_lock(void)
@@ -164,6 +165,7 @@ static inline void release_dma_lock(unsigned long flags)
 {
         spin_unlock_irqrestore(&dma_spin_lock, flags);
 }
+#endif /* CONFIG_ISA_DMA_API */
 
 /* enable/disable a specific DMA channel */
 static inline void enable_dma(unsigned int dmanr)
@@ -303,9 +305,11 @@ static inline int get_dma_residue(unsigned int dmanr)
 }
 
 
-/* These are in kernel/dma.c: */
+/* These are in kernel/dma.c because x86 uses CONFIG_GENERIC_ISA_DMA */
+#ifdef CONFIG_ISA_DMA_API
 extern int request_dma(unsigned int dmanr, const char *device_id);
 extern void free_dma(unsigned int dmanr);
+#endif
 
 /* From PCI */