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From: Olof Johansson <olof@lixom.net>
To: Keith Busch <kbusch@kernel.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>,
	Keith Busch <keith.busch@intel.com>,
	linux-pci@vger.kernel.org,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] PCI/DPC: Add pcie_ports=dpc-native parameter to bring back old behavior
Date: Wed, 23 Oct 2019 20:45:00 -0700	[thread overview]
Message-ID: <CAOesGMjXc1ezF+sC+Nc+VoXScE8kSzy1ZG_iBUBgs5RS4M0y2g@mail.gmail.com> (raw)
In-Reply-To: <20191024023704.GA3152@redsun51.ssa.fujisawa.hgst.com>

On Wed, Oct 23, 2019 at 7:37 PM Keith Busch <kbusch@kernel.org> wrote:
>
> On Wed, Oct 23, 2019 at 12:22:05PM -0700, Olof Johansson wrote:
> > In commit eed85ff4c0da7 ("PCI/DPC: Enable DPC only if AER is available"),
> > the behavior was changed such that native (kernel) handling of DPC
> > got tied to whether the kernel also handled AER. While this is what
> > the standard recommends, there are BIOSes out there that lack the DPC
> > handling since it was never required in the past.
> >
> > To make DPC still work on said platforms the same way they did before,
> > add a "pcie_ports=dpc-native" kernel parameter that can be passed in
> > if needed, while keeping defaults unchanged.
>
> If platform firmware wants to handle AER events, but the kernel enables
> the DPC capability, the ports will be trapping events that firmware is
> expecting to handle. Not that that's a bad thing: firmware is generally
> worse at handling these errors.

Right, and in particular (and what I'm looking for here): It brings
back the older behavior that some platforms rely on. :-/

> > +/*
> > + * If the user specified "pcie_ports=dpc-native", use the PCIe services
> > + * for DPC, but cuse platform defaults for the others.
>
> s/cuse/use

Thanks

> > @@ -1534,9 +1534,11 @@ static inline int pci_irqd_intx_xlate(struct irq_domain *d,
> >  #ifdef CONFIG_PCIEPORTBUS
> >  extern bool pcie_ports_disabled;
> >  extern bool pcie_ports_native;
> > +extern bool pcie_ports_dpc_native;
> >  #else
> >  #define pcie_ports_disabled  true
> >  #define pcie_ports_native    false
> > +#define pcie_ports_dpc_native        false
> >  #endif
>
> You do not have any references to pcie_ports_dpc_native outside of files that
> require CONFIG_PCIEPORTBUS, so no need to define a default.

If these are the only comments, maybe Bjorn can fixup when applying.
Bjorn; let me know if you prefer that or if you want a fresh version.
Either is fine with me.


-Olof

  reply	other threads:[~2019-10-24  3:45 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-23 19:22 [PATCH] PCI/DPC: Add pcie_ports=dpc-native parameter to bring back old behavior Olof Johansson
2019-10-24  2:37 ` Keith Busch
2019-10-24  3:45   ` Olof Johansson [this message]
2019-10-25 20:20 ` Bjorn Helgaas
2019-11-07 19:59   ` Kuppuswamy Sathyanarayanan
2019-11-07 20:09     ` Olof Johansson
2019-11-07 22:05       ` Kuppuswamy Sathyanarayanan
2019-11-07 23:59         ` Olof Johansson

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