Hi, all
According to the document of 253369(intel), the ratio is
undefined in MSR_FBC_REGSITER_ID. The following calculation is
inappropriate.
if (c->x86_model < 2)
mult = msr_lo >> 27;
There are two ways to fix this problem.
a. use the following patch. the ratio is obtained from model string.
b. revert the commit until the proper patch is available.
http://git.kernel.org/?p=linux/kernel/git/torvalds/old-2.6-bkcvs.git;a=commit;h=3e4159ab35c88aef5e063ba78796b277b762a30a
Subject: ACPI :Obtain FSB ratio from model string when model is less than 2
>From : Zhao Yakui <yakui.zhao@xxxxxxxxx>
The ratio is undefined in the register of MSR_FBC_REGSITER_ID
when the model for P4 is less than 2. The following calculation is
inappropriate.
if (c->x86_model < 2)
mult = msr_lo >> 27;
In order to support the speedstep , the FSb ratio can be obtained from
the model_id string.
For example:
The ratio is 13 for model string:"Intel(R) Pentium(R) 4 CPU 1300MHz"
http://bugzilla.kernel.org/show_bug.cgi?id=7186
Signed-off-by: Zhao Yakui <yakui.zhao@xxxxxxxxx>
---
arch/i386/kernel/cpu/cpufreq/speedstep-lib.c | 40 +++++++++++++++++++++++++--
1 file changed, 38 insertions(+), 2 deletions(-)
Index: linux-2.6.23-rc9/arch/i386/kernel/cpu/cpufreq/speedstep-lib.c
===================================================================
--- linux-2.6.23-rc9.orig/arch/i386/kernel/cpu/cpufreq/speedstep-lib.c
+++ linux-2.6.23-rc9/arch/i386/kernel/cpu/cpufreq/speedstep-lib.c
@@ -17,6 +17,7 @@
#include <asm/msr.h>
#include "speedstep-lib.h"
+#include <linux/ctype.h>
#define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, "speedstep-lib", msg)
@@ -151,7 +152,40 @@ static unsigned int pentium_core_get_fre
return (msr_tmp * fsb);
}
-
+/* When Model_id is less than 2, the FSB ratio is
+obtained from the string of model_id */
+static unsigned int p4_01_get_fsb_ratio(void)
+{
+ struct cpuinfo_x86 *c = &boot_cpu_data;
+ unsigned int fsb_m;
+ char model_id[64];
+ unsigned int freq_mhz;
+ unsigned int max_ratio;
+ char *ptr;
+ int i = 0;
+
+ ptr = model_id;
+ strncpy(ptr, c->x86_model_id, strlen(c->x86_model_id));
+ for (i = 0; i < strlen(model_id); i++)
+ model_id[i] = tolower(model_id[i]);
+ if (strstr(model_id, "mhz"))
+ fsb_m = 100;
+ else
+ fsb_m = 0;
+ if (!fsb_m) {
+ printk(KERN_DEBUG "CPU doesn't support speedstep\n");
+ return 0;
+ }
+ ptr = strstr(model_id, "hz");
+ if (ptr)
+ *ptr = '\0';
+ freq_mhz = 0;
+ ptr = strrchr(model_id, ' ');
+ if (ptr)
+ sscanf(ptr, "%d", &freq_mhz);
+ max_ratio = freq_mhz / fsb_m;
+ return max_ratio;
+}
static unsigned int pentium4_get_frequency(void)
{
@@ -189,8 +223,10 @@ static unsigned int pentium4_get_frequen
printk(KERN_DEBUG "speedstep-lib: couldn't detect FSB speed. Please send an e-mail to <linux@xxxxxxxx>\n");
/* Multiplier. */
+ /* if Model is less than 2 , the ratio is obtained from the
+ * string of model_id */
if (c->x86_model < 2)
- mult = msr_lo >> 27;
+ mult = p4_01_get_fsb_ratio();
else
mult = msr_lo >> 24;
-
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