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Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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Pull x86 fixes from Thomas Gleixner:

 - a bugfix which prevents a divide by 0 panic when the newly introduced
   try_msr_calibrate_tsc() fails

 - enablement of the Baytrail platform to utilize the newfangled msr
   based calibration

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86: tsc: Add missing Baytrail frequency to the table
  x86, tsc: Fallback to normal calibration if fast MSR calibration fails
This commit is contained in:
Linus Torvalds 2014-02-23 14:15:46 -08:00
commit 208937fdcf
3 changed files with 18 additions and 21 deletions
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2
arch/x86/include/asm/tsc.h
View File

@ -66,6 +66,6 @@ extern void tsc_save_sched_clock_state(void);
extern void tsc_restore_sched_clock_state(void);
/* MSR based TSC calibration for Intel Atom SoC platforms */
int try_msr_calibrate_tsc(unsigned long *fast_calibrate);
unsigned long try_msr_calibrate_tsc(void);
#endif /* _ASM_X86_TSC_H */

7
arch/x86/kernel/tsc.c
View File

@ -653,13 +653,10 @@ unsigned long native_calibrate_tsc(void)
/* Calibrate TSC using MSR for Intel Atom SoCs */
local_irq_save(flags);
i = try_msr_calibrate_tsc(&fast_calibrate);
fast_calibrate = try_msr_calibrate_tsc();
local_irq_restore(flags);
if (i >= 0) {
if (i == 0)
pr_warn("Fast TSC calibration using MSR failed\n");
if (fast_calibrate)
return fast_calibrate;
}
local_irq_save(flags);
fast_calibrate = quick_pit_calibrate();

30
arch/x86/kernel/tsc_msr.c
View File

@ -53,7 +53,7 @@ static struct freq_desc freq_desc_tables[] = {
/* TNG */
{ 6, 0x4a, 1, { 0, FREQ_100, FREQ_133, 0, 0, 0, 0, 0 } },
/* VLV2 */
{ 6, 0x37, 1, { 0, FREQ_100, FREQ_133, FREQ_166, 0, 0, 0, 0 } },
{ 6, 0x37, 1, { FREQ_83, FREQ_100, FREQ_133, FREQ_166, 0, 0, 0, 0 } },
/* ANN */
{ 6, 0x5a, 1, { FREQ_83, FREQ_100, FREQ_133, FREQ_100, 0, 0, 0, 0 } },
};
@ -77,21 +77,18 @@ static int match_cpu(u8 family, u8 model)
/*
* Do MSR calibration only for known/supported CPUs.
* Return values:
* -1: CPU is unknown/unsupported for MSR based calibration
* 0: CPU is known/supported, but calibration failed
* 1: CPU is known/supported, and calibration succeeded
*
* Returns the calibration value or 0 if MSR calibration failed.
*/
int try_msr_calibrate_tsc(unsigned long *fast_calibrate)
unsigned long try_msr_calibrate_tsc(void)
{
int cpu_index;
u32 lo, hi, ratio, freq_id, freq;
unsigned long res;
int cpu_index;
cpu_index = match_cpu(boot_cpu_data.x86, boot_cpu_data.x86_model);
if (cpu_index < 0)
return -1;
*fast_calibrate = 0;
return 0;
if (freq_desc_tables[cpu_index].msr_plat) {
rdmsr(MSR_PLATFORM_INFO, lo, hi);
@ -103,7 +100,7 @@ int try_msr_calibrate_tsc(unsigned long *fast_calibrate)
pr_info("Maximum core-clock to bus-clock ratio: 0x%x\n", ratio);
if (!ratio)
return 0;
goto fail;
/* Get FSB FREQ ID */
rdmsr(MSR_FSB_FREQ, lo, hi);
@ -112,16 +109,19 @@ int try_msr_calibrate_tsc(unsigned long *fast_calibrate)
pr_info("Resolved frequency ID: %u, frequency: %u KHz\n",
freq_id, freq);
if (!freq)
return 0;
goto fail;
/* TSC frequency = maximum resolved freq * maximum resolved bus ratio */
*fast_calibrate = freq * ratio;
pr_info("TSC runs at %lu KHz\n", *fast_calibrate);
res = freq * ratio;
pr_info("TSC runs at %lu KHz\n", res);
#ifdef CONFIG_X86_LOCAL_APIC
lapic_timer_frequency = (freq * 1000) / HZ;
pr_info("lapic_timer_frequency = %d\n", lapic_timer_frequency);
#endif
return res;
return 1;
fail:
pr_warn("Fast TSC calibration using MSR failed\n");
return 0;
}