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authorWilly Tarreau <w@1wt.eu>2008-02-09 23:24:08 +0100
committerThomas Gleixner <tglx@linutronix.de>2008-02-09 23:24:08 +0100
commit36445cf30686b9ea4ddf71f28057e4dd07db0e2d (patch)
tree8859c7d06e98b0c7ed03fbb934a0d40f69ad875d /arch/x86/kernel
parente78a77c38cf0ce3b8169ff6a6fd3711e81dc22c8 (diff)
x86: GEODE fix MFGPT input clock value
The GEODE MFGPT code assumed that 32kHz was 32000 Hz while the boards run on a 32.768 kHz digital watch crystal. In practise, it will not change the timer's frequency as the skew was only 2.4%, but it should provide more accurate intervals. Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Andres Salomon <dilinger@debian.org> Signed-off-by: Jordan Crouse <jordan.crouse@amd.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/x86/kernel')
-rw-r--r--arch/x86/kernel/mfgpt_32.c27
1 files changed, 13 insertions, 14 deletions
diff --git a/arch/x86/kernel/mfgpt_32.c b/arch/x86/kernel/mfgpt_32.c
index 9146b2de169..586228140b9 100644
--- a/arch/x86/kernel/mfgpt_32.c
+++ b/arch/x86/kernel/mfgpt_32.c
@@ -12,21 +12,20 @@
*/
/*
- * We are using the 32Khz input clock - its the only one that has the
+ * We are using the 32.768kHz input clock - it's the only one that has the
* ranges we find desirable. The following table lists the suitable
- * divisors and the associated hz, minimum interval
- * and the maximum interval:
+ * divisors and the associated Hz, minimum interval and the maximum interval:
*
- * Divisor Hz Min Delta (S) Max Delta (S)
- * 1 32000 .0005 2.048
- * 2 16000 .001 4.096
- * 4 8000 .002 8.192
- * 8 4000 .004 16.384
- * 16 2000 .008 32.768
- * 32 1000 .016 65.536
- * 64 500 .032 131.072
- * 128 250 .064 262.144
- * 256 125 .128 524.288
+ * Divisor Hz Min Delta (s) Max Delta (s)
+ * 1 32768 .00048828125 2.000
+ * 2 16384 .0009765625 4.000
+ * 4 8192 .001953125 8.000
+ * 8 4096 .00390625 16.000
+ * 16 2048 .0078125 32.000
+ * 32 1024 .015625 64.000
+ * 64 512 .03125 128.000
+ * 128 256 .0625 256.000
+ * 256 128 .125 512.000
*/
#include <linux/kernel.h>
@@ -45,7 +44,7 @@ static struct mfgpt_timer_t {
#define MFGPT_DIVISOR 16
#define MFGPT_SCALE 4 /* divisor = 2^(scale) */
-#define MFGPT_HZ (32000 / MFGPT_DIVISOR)
+#define MFGPT_HZ (32768 / MFGPT_DIVISOR)
#define MFGPT_PERIODIC (MFGPT_HZ / HZ)
#ifdef CONFIG_GEODE_MFGPT_TIMER