APPLIED[OSP1] Re: [SRU][B/D/OEM-B/OEM-OSP1-B][PATCH 0/1] x86/timer: Skip PIT initialization on modern chipsets

[Timo Aaltonen]

On 7.11.2019 10.05, You-Sheng Yang wrote:
> From: You-Sheng Yang <vicamo at gmail.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/1851216
> 
> [Impact]
> Some recent platform seem to have an unstable HPET, which is used to
> calibrate TSC but turns out to mark an actual stable TSC clocksource as
> unstable, and then fallback to that unstable HPET as main clocksource. A
> previous fix was proposed in bug 1840239, which is then observed to hang
> platforms with modern chipsets including Skylake and ApolloLake at early
> boot stage when HPET is disabled.
> 
> [Fix]
> Commit c8c4076723da "x86/timer: Skip PIT initialization on modern chipsets"
> included in v5.3-rc1 to be backported.
> 
> [Test Case]
> Boot with kernel built with this change, and see if it will hang right
> after grub loaded initramfs image.
> 
> [Regression Risk]
> Low. This change detects the hardware that requires explicit PIT
> initialization skip and skip it. For those unaffected systems, they
> remain unaffected.
> 
> Thomas Gleixner (1):
>   x86/timer: Skip PIT initialization on modern chipsets
> 
>  arch/x86/include/asm/apic.h    |  2 ++
>  arch/x86/include/asm/time.h    |  1 +
>  arch/x86/kernel/apic/apic.c    | 27 +++++++++++++++++++++++++++
>  arch/x86/kernel/apic/io_apic.c |  4 ++++
>  arch/x86/kernel/i8253.c        | 25 ++++++++++++++++++++++++-
>  arch/x86/kernel/time.c         |  7 +++++--
>  6 files changed, 63 insertions(+), 3 deletions(-)
> 

applied to osp1 oem-next, thanks

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t