diff options
Diffstat (limited to 'include/asm-generic/barrier.h')
| -rw-r--r-- | include/asm-generic/barrier.h | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/include/asm-generic/barrier.h b/include/asm-generic/barrier.h index 640f09479bdf..4c2c1b830344 100644 --- a/include/asm-generic/barrier.h +++ b/include/asm-generic/barrier.h @@ -251,5 +251,16 @@ do { \ #define pmem_wmb() wmb() #endif +/* + * ioremap_wc() maps I/O memory as memory with write-combining attributes. For + * this kind of memory accesses, the CPU may wait for prior accesses to be + * merged with subsequent ones. In some situation, such wait is bad for the + * performance. io_stop_wc() can be used to prevent the merging of + * write-combining memory accesses before this macro with those after it. + */ +#ifndef io_stop_wc +#define io_stop_wc do { } while (0) +#endif + #endif /* !__ASSEMBLY__ */ #endif /* __ASM_GENERIC_BARRIER_H */ |