From: Vipul Kumar vipul_kumar@mentor.com

'commit f3a02ecebed7 ("x86/tsc: Set TSC_KNOWN_FREQ and TSC_RELIABLE flags on Intel Atom SoCs")', causing time drift for Bay trail SoC. These flags are set for SoCs having cpuid_level 0x15 or more. Bay trail is having cpuid_level 0xb.

So, unset both flags to make sure the clocksource calibration can be done.

Signed-off-by: Vipul Kumar vipul_kumar@mentor.com Cc: stable@vger.kernel.org # 4.14+ --- - Changes in v2: - Added linux-stable along with kernel version in CC --- arch/x86/kernel/tsc_msr.c | 3 +++ 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kernel/tsc_msr.c b/arch/x86/kernel/tsc_msr.c index e0cbe4f2af49..1ca27c28db98 100644 --- a/arch/x86/kernel/tsc_msr.c +++ b/arch/x86/kernel/tsc_msr.c @@ -112,6 +112,9 @@ unsigned long cpu_khz_from_msr(void) lapic_timer_period = (freq * 1000) / HZ; #endif

+ if (boot_cpu_data.cpuid_level < 0x15) + return res; + /* * TSC frequency determined by MSR is always considered "known" * because it is reported by HW.