Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [PATCH] x86/PCI: Convert force_disable_hpet() to standard quirk | Date | Wed, 25 Nov 2020 13:46:23 +0100 |
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On Thu, Nov 19 2020 at 12:19, Bjorn Helgaas wrote: > 62187910b0fc ("x86/intel: Add quirk to disable HPET for the Baytrail > platform") implemented force_disable_hpet() as a special early quirk. > These run before the PCI core is initialized and depend on the > x86/pci/early.c accessors that use I/O ports 0xcf8 and 0xcfc. > > But force_disable_hpet() doesn't need to be one of these special early > quirks. It merely sets "boot_hpet_disable", which is tested by > is_hpet_capable(), which is only used by hpet_enable() and hpet_disable(). > hpet_enable() is an fs_initcall(), so it runs after the PCI core is > initialized.
hpet_enable() is not an fs_initcall(). hpet_late_init() is and that invokes hpet_enable() only for the case that ACPI did not advertise it and the force_hpet quirk provided a base address.
But hpet_enable() is also invoked via:
start_kernel() late_time_init() x86_late_time_init() hpet_time_init()
which is way before the PCI core is available and we really don't want to set it up there if it's known to be broken :)
Now the more interesting question is why this needs to be a PCI quirk in the first place. Can't we just disable the HPET based on family/model quirks?
e0748539e3d5 ("x86/intel: Disable HPET on Intel Ice Lake platforms") f8edbde885bb ("x86/intel: Disable HPET on Intel Coffee Lake H platforms") fc5db58539b4 ("x86/quirks: Disable HPET on Intel Coffe Lake platforms") 62187910b0fc ("x86/intel: Add quirk to disable HPET for the Baytrail platform")
I might be missing something here, but in general on anything modern HPET is mostly useless.
Thanks,
tglx
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