[mips-sjhill:mti-next 31/35] dma-default.c:(.text+0xb958): undefined reference to `hw_coherentio'

[kbuild test robot <fengguang.wu@intel.com>]

tree:   git://git.linux-mips.org/pub/scm/sjhill/linux-sjhill mti-next
head:   76965291af22d5e06b8ffff677cfe2b227a9487a
commit: 5e8848b05d0c0a6854c7de9f55122ccf2f47a248 [31/35] MIPS: Add option to 
disable software I/O coherency.
config: make ARCH=mips allnoconfig

All error/warnings:

arch/mips/built-in.o: In function `mips_dma_map_sg':
dma-default.c:(.text+0xb310): undefined reference to `coherentio'
dma-default.c:(.text+0xb360): undefined reference to `coherentio'
arch/mips/built-in.o: In function `mips_dma_map_page':
dma-default.c:(.text+0xb430): undefined reference to `coherentio'
dma-default.c:(.text+0xb434): undefined reference to `coherentio'
arch/mips/built-in.o: In function `mips_dma_unmap_sg':
dma-default.c:(.text+0xb58c): undefined reference to `coherentio'
arch/mips/built-in.o:dma-default.c:(.text+0xb5bc): more undefined references to 
`coherentio' follow
arch/mips/built-in.o: In function `mips_dma_free_coherent':
dma-default.c:(.text+0xb958): undefined reference to `hw_coherentio'
dma-default.c:(.text+0xb95c): undefined reference to `hw_coherentio'
arch/mips/built-in.o: In function `mips_dma_alloc_coherent':
dma-default.c:(.text+0xbae8): undefined reference to `coherentio'
dma-default.c:(.text+0xbaec): undefined reference to `coherentio'
dma-default.c:(.text+0xbb3c): undefined reference to `hw_coherentio'
dma-default.c:(.text+0xbb40): undefined reference to `hw_coherentio'
arch/mips/built-in.o: In function `mips_dma_unmap_page':
dma-default.c:(.text+0xbb6c): undefined reference to `coherentio'
dma-default.c:(.text+0xbb70): undefined reference to `coherentio'
arch/mips/built-in.o: In function `mips_dma_sync_single_for_cpu':
dma-default.c:(.text+0xbbf8): undefined reference to `coherentio'
dma-default.c:(.text+0xbbfc): undefined reference to `coherentio'
arch/mips/built-in.o: In function `mips_dma_sync_single_for_device':
dma-default.c:(.text+0xbc84): undefined reference to `coherentio'
arch/mips/built-in.o:dma-default.c:(.text+0xbc88): more undefined references to 
`coherentio' follow

---
0-DAY kernel build testing backend         Open Source Technology Center
Fengguang Wu, Yuanhan Liu                              Intel Corporation