Some Coffee Lake platforms have skewed HPET timer once the SoCs entered PC10, and marked TSC as unstable clocksource as result.
Harry Pan identified it's a firmware bug [1]. To prevent creating a circular dependency between HPET and TSC, let's disable HPET on affected platforms. [1]: https://lore.kernel.org/lkml/20190516090651.1396-1-harry....@intel.com/ Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=203183 Signed-off-by: Kai-Heng Feng <kai.heng.f...@canonical.com> --- arch/x86/kernel/hpet.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c index c6f791bc481e..07e9ec6f85b6 100644 --- a/arch/x86/kernel/hpet.c +++ b/arch/x86/kernel/hpet.c @@ -7,7 +7,9 @@ #include <linux/cpu.h> #include <linux/irq.h> +#include <asm/cpu_device_id.h> #include <asm/hpet.h> +#include <asm/intel-family.h> #include <asm/time.h> #undef pr_fmt @@ -806,6 +808,12 @@ static bool __init hpet_counting(void) return false; } +static const struct x86_cpu_id hpet_blacklist[] __initconst = { + { X86_VENDOR_INTEL, 6, INTEL_FAM6_KABYLAKE_MOBILE }, + { X86_VENDOR_INTEL, 6, INTEL_FAM6_KABYLAKE_DESKTOP }, + { } +}; + /** * hpet_enable - Try to setup the HPET timer. Returns 1 on success. */ @@ -819,6 +827,9 @@ int __init hpet_enable(void) if (!is_hpet_capable()) return 0; + if (!hpet_force_user && x86_match_cpu(hpet_blacklist)) + return 0; + hpet_set_mapping(); if (!hpet_virt_address) return 0; -- 2.17.1
