From: Kai-Heng Feng kai.heng.feng@canonical.com
commit fc5db58539b49351e76f19817ed1102bf7c712d0 upstream.
Some Coffee Lake platforms have a skewed HPET timer once the SoCs entered PC10, which in consequence marks TSC as unstable because HPET is used as watchdog clocksource for TSC.
Harry Pan tried to work around it in the clocksource watchdog code [1] thereby creating a circular dependency between HPET and TSC. This also ignores the fact, that HPET is not only unsuitable as watchdog clocksource on these systems, it becomes unusable in general.
Disable HPET on affected platforms.
Suggested-by: Feng Tang feng.tang@intel.com Signed-off-by: Kai-Heng Feng kai.heng.feng@canonical.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Cc: stable@vger.kernel.org Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=203183 Link: https://lore.kernel.org/lkml/20190516090651.1396-1-harry.pan@intel.com/ [1] Link: https://lkml.kernel.org/r/20191016103816.30650-1-kai.heng.feng@canonical.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/kernel/early-quirks.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/arch/x86/kernel/early-quirks.c +++ b/arch/x86/kernel/early-quirks.c @@ -681,6 +681,8 @@ static struct chipset early_qrk[] __init */ { PCI_VENDOR_ID_INTEL, 0x0f00, PCI_CLASS_BRIDGE_HOST, PCI_ANY_ID, 0, force_disable_hpet}, + { PCI_VENDOR_ID_INTEL, 0x3ec4, + PCI_CLASS_BRIDGE_HOST, PCI_ANY_ID, 0, force_disable_hpet}, { PCI_VENDOR_ID_BROADCOM, 0x4331, PCI_CLASS_NETWORK_OTHER, PCI_ANY_ID, 0, apple_airport_reset}, {}