diff options
Diffstat (limited to 'arch/x86/kernel/tsc_msr.c')
| -rw-r--r-- | arch/x86/kernel/tsc_msr.c | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/arch/x86/kernel/tsc_msr.c b/arch/x86/kernel/tsc_msr.c index 0fe720d64fef..19afdbd7d0a7 100644 --- a/arch/x86/kernel/tsc_msr.c +++ b/arch/x86/kernel/tsc_msr.c @@ -100,5 +100,24 @@ unsigned long cpu_khz_from_msr(void) #ifdef CONFIG_X86_LOCAL_APIC lapic_timer_frequency = (freq * 1000) / HZ; #endif + + /* + * TSC frequency determined by MSR is always considered "known" + * because it is reported by HW. + * Another fact is that on MSR capable platforms, PIT/HPET is + * generally not available so calibration won't work at all. + */ + setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ); + + /* + * Unfortunately there is no way for hardware to tell whether the + * TSC is reliable. We were told by silicon design team that TSC + * on Atom SoCs are always "reliable". TSC is also the only + * reliable clocksource on these SoCs (HPET is either not present + * or not functional) so mark TSC reliable which removes the + * requirement for a watchdog clocksource. + */ + setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE); + return res; } |