Commit-ID: 4635fdc696a8e89eead3ea1712ae6ada38538d40 Gitweb: http://git.kernel.org/tip/4635fdc696a8e89eead3ea1712ae6ada38538d40 Author: Bin Gao <bin.gao@xxxxxxxxxxxxxxx> AuthorDate: Tue, 15 Nov 2016 12:27:23 -0800 Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> CommitDate: Fri, 18 Nov 2016 10:58:30 +0100 x86/tsc: Mark Intel ATOM_GOLDMONT TSC reliable On Intel GOLDMONT Atom SoC TSC is the only available clocksource, so there is no way to do software calibration or have a watchdog clocksource for it. Software calibration is already disabled via the TSC_KNOWN_FREQ flag, but the watchdog requirement still persists, so such systems cannot switch to high resolution/nohz mode. Mark it reliable, so it becomes usable. Hardware teams confirmed that this is safe on that SoC. Signed-off-by: Bin Gao <bin.gao@xxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/1479241644-234277-4-git-send-email-bin.gao@xxxxxxxxxxxxxxx Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> --- arch/x86/kernel/tsc.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index e58c319..f4dfdaa 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -709,6 +709,13 @@ unsigned long native_calibrate_tsc(void) */ setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ); + /* + * For Atom SoCs TSC is the only reliable clocksource. + * Mark TSC reliable so no watchdog on it. + */ + if (boot_cpu_data.x86_model == INTEL_FAM6_ATOM_GOLDMONT) + setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE); + return crystal_khz * ebx_numerator / eax_denominator; } -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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