README: document the requirements for CONFIG_SYS_HZ

CONFIG_SYS_HZ must be 1000, and get_timer() must therefore return ms.
Document this.

README text provided by Tom Rini.

Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>

diff --git a/README b/README
index 1d5182825241f42e8c8256daf1f7c88aec2c90ec..57010161f57f5a719430b06a64b75fd27980b16d 100644 (file)
--- a/README
+++ b/README
@@ -496,6 +496,13 @@ The following options need to be configured:
                exists, unlike the similar options in the Linux kernel. Do not
                set these options unless they apply!
 
+- CPU timer options:
+               CONFIG_SYS_HZ
+
+               The frequency of the timer returned by get_timer().
+               get_timer() must operate in milliseconds and this CONFIG
+               option must be set to 1000.
+
 - Linux Kernel Interface:
                CONFIG_CLOCKS_IN_MHZ