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Date:   Thu, 27 Feb 2020 16:49:30 -0600
From:   Bjorn Helgaas <helgaas@kernel.org>
To:     Sean V Kelley <sean.v.kelley@linux.intel.com>
Cc:     tglx@linutronix.de, corbet@lwn.net, mingo@redhat.com, bp@alien8.de,
        x86@kernel.org, linux-pci@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
        kar.hin.ong@ni.com, sassmann@kpanic.de
Subject: Re: [PATCH v2 0/2] pci: Add boot interrupt quirk mechanism for Xeon
 chipsets
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On Thu, Feb 20, 2020 at 11:29:28AM -0800, Sean V Kelley wrote:
> Changes since v1 [1]:
> 
> - Correct Documentation section title for 6300ESB chipset.
> (Jonathan Derrick)
> 
> - Use consistent abbreviations in comments for IO-APIC and Core IO.
> (Andy Shevchenko)
> 
> - Retained Reviewed-by tag due to no technical changes.
> 
> [1]: https://lore.kernel.org/lkml/20200214213313.66622-1-sean.v.kelley@linux.intel.com/
> 
> Bjorn, I'm open for it to go to stable as well.
> 
> --
> 
> When IRQ lines on secondary or higher IO-APICs are masked (e.g.,
> Real-Time threaded interrupts), many chipsets redirect IRQs on
> this line to the legacy PCH and in turn the base IO-APIC in the
> system. The unhandled interrupts on the base IO-APIC will be
> identified by the Linux kernel as Spurious Interrupts and can
> lead to disabled IRQ lines.
> 
> Disabling this legacy PCI interrupt routing is chipset-specific and
> varies in mechanism between chipset vendors and across generations.
> In some cases the mechanism is exposed to BIOS but not all BIOS
> vendors chose to pick it up. With the increasing usage of RT as it
> marches towards mainline, additional issues have been raised with
> more recent Xeon chipsets.
> 
> This patchset disables the boot interrupt on these Xeon chipsets where
> this is possible with an additional mechanism. In addition, this
> patchset includes documentation covering the background of this quirk.
> 
> 
> Sean V Kelley (2):
>   pci: Add boot interrupt quirk mechanism for Xeon chipsets
>   Documentation:PCI: Add background on Boot Interrupts
> 
>  Documentation/PCI/boot-interrupts.rst | 153 ++++++++++++++++++++++++++
>  Documentation/PCI/index.rst           |   1 +
>  drivers/pci/quirks.c                  |  80 ++++++++++++--
>  3 files changed, 227 insertions(+), 7 deletions(-)
>  create mode 100644 Documentation/PCI/boot-interrupts.rst

Applied to pci/interrupts for v5.7.  I added a stable tag.

Thanks a lot; this is really a nice piece of work!