diff options
| author | Willy Tarreau <w@1wt.eu> | 2008-02-09 23:24:08 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2008-02-09 23:24:08 +0100 |
| commit | 36445cf30686b9ea4ddf71f28057e4dd07db0e2d (patch) | |
| tree | 8859c7d06e98b0c7ed03fbb934a0d40f69ad875d | |
| parent | x86: GEODE: MFGPT: Minor cleanups (diff) | |
| download | linux-36445cf30686b9ea4ddf71f28057e4dd07db0e2d.tar.xz linux-36445cf30686b9ea4ddf71f28057e4dd07db0e2d.zip | |
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>
| -rw-r--r-- | arch/x86/kernel/mfgpt_32.c | 27 |
1 files changed, 13 insertions, 14 deletions
diff --git a/arch/x86/kernel/mfgpt_32.c b/arch/x86/kernel/mfgpt_32.c index 9146b2de1698..586228140b9e 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 |