[CPUFREQ] p4-clockmod reports wrong frequency.

http://bugzilla.kernel.org/show_bug.cgi?id=10968

[ Updated for current tree, and fixed compile failure
  when p4-clockmod was built modular -- davej]

From: Matthias-Christian Ott <ott@mirix.org>
Signed-off-by: Dominik Brodowski <linux@brodo.de>
Signed-off-by: Dave Jones <davej@redhat.com>

arch/x86/include/asm/timer.h

@@ -11,8 +11,8 @@ unsigned long native_calibrate_tsc(void);
 
 #ifdef CONFIG_X86_32
 extern int timer_ack;
+#endif
 extern int recalibrate_cpu_khz(void);
-#endif /* CONFIG_X86_32 */
 
 extern int no_timer_check;
 

arch/x86/kernel/cpu/cpufreq/p4-clockmod.c

@@ -31,6 +31,7 @@
 
 #include <asm/processor.h>
 #include <asm/msr.h>
+#include <asm/timer.h>
 
 #include "speedstep-lib.h"
 
@@ -224,6 +225,12 @@ static int cpufreq_p4_cpu_init(struct cpufreq_policy *policy)
 		dprintk("has errata -- disabling low frequencies\n");
 	}
 
+	if (speedstep_detect_processor() == SPEEDSTEP_CPU_P4D &&
+	    c->x86_model < 2) {
+		/* switch to maximum frequency and measure result */
+		cpufreq_p4_setdc(policy->cpu, DC_DISABLE);
+		recalibrate_cpu_khz();
+	}
 	/* get max frequency */
 	stock_freq = cpufreq_p4_get_frequency(c);
 	if (!stock_freq)

arch/x86/kernel/cpu/cpufreq/speedstep-lib.c

@@ -16,6 +16,7 @@
 #include <linux/slab.h>
 
 #include <asm/msr.h>
+#include <asm/tsc.h>
 #include "speedstep-lib.h"
 
 #define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, \
@@ -178,6 +179,15 @@ static unsigned int pentium4_get_frequency(void)
 	u32 msr_lo, msr_hi, mult;
 	unsigned int fsb = 0;
 	unsigned int ret;
+	u8 fsb_code;
+
+	/* Pentium 4 Model 0 and 1 do not have the Core Clock Frequency
+	 * to System Bus Frequency Ratio Field in the Processor Frequency
+	 * Configuration Register of the MSR. Therefore the current
+	 * frequency cannot be calculated and has to be measured.
+	 */
+	if (c->x86_model < 2)
+		return cpu_khz;
 
 	rdmsr(0x2c, msr_lo, msr_hi);
 
@@ -188,10 +198,7 @@ static unsigned int pentium4_get_frequency(void)
 	 * revision #12 in Table B-1: MSRs in the Pentium 4 and
 	 * Intel Xeon Processors, on page B-4 and B-5.
 	 */
-	if (c->x86_model < 2)
-		fsb = 100 * 1000;
-	else {
-		u8 fsb_code = (msr_lo >> 16) & 0x7;
+	fsb_code = (msr_lo >> 16) & 0x7;
 	switch (fsb_code) {
 	case 0:
 		fsb = 100 * 1000;
@@ -203,7 +210,6 @@ static unsigned int pentium4_get_frequency(void)
 		fsb = 200 * 1000;
 		break;
 	}
-	}
 
 	if (!fsb)
 		printk(KERN_DEBUG PFX "couldn't detect FSB speed. "

arch/x86/kernel/tsc.c

@@ -523,8 +523,6 @@ unsigned long native_calibrate_tsc(void)
 	return tsc_pit_min;
 }
 
-#ifdef CONFIG_X86_32
-/* Only called from the Powernow K7 cpu freq driver */
 int recalibrate_cpu_khz(void)
 {
 #ifndef CONFIG_SMP
@@ -546,7 +544,6 @@ int recalibrate_cpu_khz(void)
 
 EXPORT_SYMBOL(recalibrate_cpu_khz);
 
-#endif /* CONFIG_X86_32 */
 
 /* Accelerators for sched_clock()
  * convert from cycles(64bits) => nanoseconds (64bits)