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| author | Bin Gao <bin.gao@linux.intel.com> | 2016-11-15 21:27:24 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2016-11-18 10:58:31 +0100 |
| commit | f3a02ecebed7df7d5d68898628dea7a3bfcf03e3 (patch) | |
| tree | b8631d7c3aef3307b593e12b5e3255df138eac9d /arch/x86/platform | |
| parent | x86/tsc: Mark Intel ATOM_GOLDMONT TSC reliable (diff) | |
| download | linux-f3a02ecebed7df7d5d68898628dea7a3bfcf03e3.tar.xz linux-f3a02ecebed7df7d5d68898628dea7a3bfcf03e3.zip | |
x86/tsc: Set TSC_KNOWN_FREQ and TSC_RELIABLE flags on Intel Atom SoCs
TSC on Intel Atom SoCs capable of determining TSC frequency by MSR is
reliable and the frequency is known (provided by HW).
On these platforms PIT/HPET is generally not available so calibration won't
work at all and there is no other clocksource to act as a watchdog for the
TSC, so we have no other choice than to trust it.
Set both X86_FEATURE_TSC_KNOWN_FREQ and X86_FEATURE_TSC_RELIABLE flags to
make sure the calibration is skipped and no watchdog is required.
Signed-off-by: Bin Gao <bin.gao@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1479241644-234277-5-git-send-email-bin.gao@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/x86/platform')
| -rw-r--r-- | arch/x86/platform/intel-mid/mfld.c | 9 | ||||
| -rw-r--r-- | arch/x86/platform/intel-mid/mrfld.c | 8 |
2 files changed, 13 insertions, 4 deletions
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; } |