From: Paolo 'Blaisorblade' Giarrusso For both i386 and x86_64, copy from arch/$ARCH/lib/delay.c comments about the used magic constants, plus a few other niceties. Signed-off-by: Paolo 'Blaisorblade' Giarrusso Cc: Andi Kleen Signed-off-by: Andrew Morton --- include/asm-i386/delay.h | 5 ++++- include/asm-x86_64/delay.h | 5 ++++- 2 files changed, 8 insertions(+), 2 deletions(-) diff -puN include/asm-i386/delay.h~i386-x86_64-comment-magic-constants-in-delayh include/asm-i386/delay.h --- a/include/asm-i386/delay.h~i386-x86_64-comment-magic-constants-in-delayh +++ a/include/asm-i386/delay.h @@ -7,6 +7,7 @@ * Delay routines calling functions in arch/i386/lib/delay.c */ +/* Undefined functions to get compile-time errors */ extern void __bad_udelay(void); extern void __bad_ndelay(void); @@ -15,10 +16,12 @@ extern void __ndelay(unsigned long nsecs extern void __const_udelay(unsigned long usecs); extern void __delay(unsigned long loops); +/* 0x10c7 is 2**32 / 1000000 (rounded up) */ #define udelay(n) (__builtin_constant_p(n) ? \ ((n) > 20000 ? __bad_udelay() : __const_udelay((n) * 0x10c7ul)) : \ __udelay(n)) - + +/* 0x5 is 2**32 / 1000000000 (rounded up) */ #define ndelay(n) (__builtin_constant_p(n) ? \ ((n) > 20000 ? __bad_ndelay() : __const_udelay((n) * 5ul)) : \ __ndelay(n)) diff -puN include/asm-x86_64/delay.h~i386-x86_64-comment-magic-constants-in-delayh include/asm-x86_64/delay.h --- a/include/asm-x86_64/delay.h~i386-x86_64-comment-magic-constants-in-delayh +++ a/include/asm-x86_64/delay.h @@ -7,18 +7,21 @@ * Delay routines calling functions in arch/x86_64/lib/delay.c */ +/* Undefined functions to get compile-time errors */ extern void __bad_udelay(void); extern void __bad_ndelay(void); extern void __udelay(unsigned long usecs); -extern void __ndelay(unsigned long usecs); +extern void __ndelay(unsigned long nsecs); extern void __const_udelay(unsigned long usecs); extern void __delay(unsigned long loops); +/* 0x10c7 is 2**32 / 1000000 (rounded up) */ #define udelay(n) (__builtin_constant_p(n) ? \ ((n) > 20000 ? __bad_udelay() : __const_udelay((n) * 0x10c7ul)) : \ __udelay(n)) +/* 0x5 is 2**32 / 1000000000 (rounded up) */ #define ndelay(n) (__builtin_constant_p(n) ? \ ((n) > 20000 ? __bad_ndelay() : __const_udelay((n) * 5ul)) : \ __ndelay(n)) _