davinci: explain CLOCK_TICK_RATE of 27MHz in include/mach/timex.h

Commit Message

Sekhar Nori Nov. 23, 2009, 9:57 a.m. UTC

None

Patch

diff --git a/arch/arm/mach-davinci/include/mach/timex.h b/arch/arm/mach-davinci/include/mach/timex.h
index 5282756..9b88529 100644
--- a/arch/arm/mach-davinci/include/mach/timex.h
+++ b/arch/arm/mach-davinci/include/mach/timex.h
@@ -11,7 +11,12 @@ 
 #ifndef __ASM_ARCH_TIMEX_H
 #define __ASM_ARCH_TIMEX_H
 
-/* The source frequency for the timers is the 27MHz clock */
+/*
+ * Alert: Not all timers of the DaVinci family run at a frequency of 27MHz,
+ * but we should be fine as long as CLOCK_TICK_RATE or LATCH (see include/
+ * linux/jiffies.h) are not used directly in code. Currently none of the
+ * code relevant to DaVinci platform depends on these values directly.
+ */
 #define CLOCK_TICK_RATE 27000000
 
 #endif /* __ASM_ARCH_TIMEX_H__ */