Messages in this thread Patch in this message | | | From | Feng Tang <> | Date | Wed, 9 Oct 2019 13:58:55 +0800 | Subject | Re: [PATCH] x86/hpet: Disable HPET on Intel Coffe Lake |
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Hi Kai-Heng,
On Thu, Aug 29, 2019 at 5:14 PM Kai-Heng Feng <kai.heng.feng@canonical.com> wrote: > > 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.
Sorry for chiming late.
We have disabled the HPET for Baytrail platforms in commit 62187910b0fc : x86/intel: Add quirk to disable HPET for the Baytrail platform
Which added a quirk in @@ -567,6 +577,12 @@ static struct chipset early_qrk[] __initdata = { + /* + * HPET on current version of Baytrail platform has accuracy + * problems, disable it for now: + */ + { PCI_VENDOR_ID_INTEL, 0x0f00, + PCI_CLASS_BRIDGE_HOST, PCI_ANY_ID, 0, force_disable_hpet},
So maybe we can unify the method to disable HPET. (btw, I have no idea about the healthy info of HPET for Kabylake, just want to comment on the disabling method).
Thanks, Feng
> > [1]: https://lore.kernel.org/lkml/20190516090651.1396-1-harry.pan@intel.com/ > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=203183 > > Signed-off-by: Kai-Heng Feng <kai.heng.feng@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 >
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