commit 9138dccbb9f39f12474554ef93dcc24de2e9c8f6
author Deepak Saxena <dsaxena@plexity.net> Tue Aug 23 13:30:29 2005 -0700
committer Linus Torvalds <torvalds@g5.osdl.org> Tue Aug 23 20:06:33 2005 -0700
tree c7e606155b97f5a7e0a8808b1e2cbf37ea0162ac
parent d10689b68aff7b48e3de1a3f7fcd6567bd2905af

[PATCH] Fix IXP4xx CLOCK_TICK_RATE

As pointed out in the following thread, the CLOCK_TICK_RATE setting for
IXP4xx is incorrect b/c the HW ignores the lowest 2 bits of the LATCH
value.

   http://lists.arm.linux.org.uk/pipermail/linux-arm-kernel/2005-August/030950.html

Tnx to George Anziger and Egil Hjelmeland for finding the issue.

Signed-off-by: Deepak Saxena <dsaxena@plexity.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/asm-arm/arch-ixp4xx/timex.h

diff --git a/include/asm-arm/arch-ixp4xx/timex.h b/include/asm-arm/arch-ixp4xx/timex.h
index 38c9d77..3745e35 100644
--- a/include/asm-arm/arch-ixp4xx/timex.h
+++ b/include/asm-arm/arch-ixp4xx/timex.h
@@ -7,7 +7,9 @@
 
 /*
  * We use IXP425 General purpose timer for our timer needs, it runs at 
- * 66.66... MHz
+ * 66.66... MHz. We do a convulted calculation of CLOCK_TICK_RATE b/c the
+ * timer register ignores the bottom 2 bits of the LATCH value.
  */
-#define CLOCK_TICK_RATE (66666666)
+#define FREQ 66666666
+#define CLOCK_TICK_RATE (((FREQ / HZ & ~IXP4XX_OST_RELOAD_MASK) + 1) * HZ)