diff options
| -rw-r--r-- | arch/x86/kernel/tsc_msr.c | 19 | ||||
| -rw-r--r-- | arch/x86/platform/intel-mid/mfld.c | 9 | ||||
| -rw-r--r-- | arch/x86/platform/intel-mid/mrfld.c | 8 |
3 files changed, 32 insertions, 4 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; } diff --git a/arch/x86/platform/intel-mid/mfld.c b/arch/x86/platform/intel-mid/mfld.c index 1eb47b6298c2..e793fe509971 100644 --- a/arch/x86/platform/intel-mid/mfld.c +++ b/arch/x86/platform/intel-mid/mfld.c @@ -49,8 +49,13 @@ static unsigned long __init mfld_calibrate_tsc(void) fast_calibrate = ratio * fsb; pr_debug("read penwell tsc %lu khz\n", fast_calibrate); lapic_timer_frequency = fsb * 1000 / HZ; - /* mark tsc clocksource as reliable */ - set_cpu_cap(&boot_cpu_data, X86_FEATURE_TSC_RELIABLE); + + /* + * TSC on Intel Atom SoCs is reliable and of known frequency. + * See tsc_msr.c for details. + */ + setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ); + setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE); return fast_calibrate; } diff --git a/arch/x86/platform/intel-mid/mrfld.c b/arch/x86/platform/intel-mid/mrfld.c index 59253db41bbc..e0607c77a1bd 100644 --- a/arch/x86/platform/intel-mid/mrfld.c +++ b/arch/x86/platform/intel-mid/mrfld.c @@ -78,8 +78,12 @@ static unsigned long __init tangier_calibrate_tsc(void) pr_debug("Setting lapic_timer_frequency = %d\n", lapic_timer_frequency); - /* mark tsc clocksource as reliable */ - set_cpu_cap(&boot_cpu_data, X86_FEATURE_TSC_RELIABLE); + /* + * TSC on Intel Atom SoCs is reliable and of known frequency. + * See tsc_msr.c for details. + */ + setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ); + setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE); return fast_calibrate; } |