[PATCH] x86: comment magic constants in delay.h

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 <blaisorblade@yahoo.it>
Signed-off-by: Andi Kleen <ak@suse.de>

 include/asm-i386/delay.h   |    5 ++++-
 include/asm-x86_64/delay.h |    5 ++++-
 2 files changed, 8 insertions(+), 2 deletions(-)

2 files changed, 8 insertions, 2 deletions

diff --git a/include/asm-i386/delay.h b/include/asm-i386/delay.h
index b1c7650dc7b9..9ae5e3782ed8 100644
--- a/include/asm-i386/delay.h
+++ b/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 --git a/include/asm-x86_64/delay.h b/include/asm-x86_64/delay.h
index 40146f611ccb..c2669f1f5529 100644
--- a/include/asm-x86_64/delay.h
+++ b/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))