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Commit 36445cf3 authored by Willy Tarreau's avatar Willy Tarreau Committed by Thomas Gleixner
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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: default avatarWilly Tarreau <w@1wt.eu>
Signed-off-by: default avatarAndres Salomon <dilinger@debian.org>
Signed-off-by: default avatarJordan Crouse <jordan.crouse@amd.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent e78a77c3

arch/x86/kernel/mfgpt_32.c

+13 −14
Original line number Diff line number Diff line
@@ -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