From: Rob Herring <robh@kernel.org>
To: Mike Rapoport <rppt@kernel.org>, Boqun Feng <boqun.feng@gmail.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>,
Arnd Bergmann <arnd@arndb.de>, Marc Zyngier <maz@kernel.org>,
Russell King <linux@armlinux.org.uk>,
Andrew Lunn <andrew@lunn.ch>,
Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>,
Gregory Clement <gregory.clement@bootlin.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
"K. Y. Srinivasan" <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
Wei Liu <wei.liu@kernel.org>,
Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
Robin Murphy <robin.murphy@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Jon Derrick <jonathan.derrick@intel.com>,
Sunil Muthuswamy <sunilmut@microsoft.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org,
linux-pci@vger.kernel.org, linux-hyperv@vger.kernel.org
Subject: Re: [RFC v2 1/7] PCI: Introduce pci_host_bridge::domain_nr
Date: Tue, 4 May 2021 09:34:54 -0500 [thread overview]
Message-ID: <CAL_JsqLMAyUEZgLjiKmNL2ioTYJwj-TbTWFJmEi7pynKZHXmoQ@mail.gmail.com> (raw)
In-Reply-To: <YJDYrn7Nt+xyHbyr@kernel.org>
On Tue, May 4, 2021 at 12:16 AM Mike Rapoport <rppt@kernel.org> wrote:
>
> On Mon, May 03, 2021 at 10:46:29PM +0800, Boqun Feng wrote:
> > Currently we retrieve the PCI domain number of the host bridge from the
> > bus sysdata (or pci_config_window if PCI_DOMAINS_GENERIC=y). Actually
> > we have the information at PCI host bridge probing time, and it makes
> > sense that we store it into pci_host_bridge. One benefit of doing so is
> > the requirement for supporting PCI on Hyper-V for ARM64, because the
> > host bridge of Hyper-V doesnt' have pci_config_window, whereas ARM64 is
> > a PCI_DOMAINS_GENERIC=y arch, so we cannot retrieve the PCI domain
> > number from pci_config_window on ARM64 Hyper-V guest.
> >
> > As the preparation for ARM64 Hyper-V PCI support, we introduce the
> > domain_nr in pci_host_bridge, and set it properly at probing time, then
> > for PCI_DOMAINS_GENERIC=y archs, bus domain numbers are set by the
> > bridge domain_nr.
> >
> > Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
> > ---
> > arch/arm/kernel/bios32.c | 2 ++
> > arch/arm/mach-dove/pcie.c | 2 ++
> > arch/arm/mach-mv78xx0/pcie.c | 2 ++
> > arch/arm/mach-orion5x/pci.c | 2 ++
> > arch/arm64/kernel/pci.c | 3 +--
> > arch/mips/pci/pci-legacy.c | 2 ++
> > arch/mips/pci/pci-xtalk-bridge.c | 2 ++
> > drivers/pci/controller/pci-ftpci100.c | 2 ++
> > drivers/pci/controller/pci-mvebu.c | 2 ++
> > drivers/pci/pci.c | 4 ++--
> > drivers/pci/probe.c | 7 ++++++-
> > include/linux/pci.h | 11 ++++++++---
> > 12 files changed, 33 insertions(+), 8 deletions(-)
> >
> > diff --git a/arch/arm/kernel/bios32.c b/arch/arm/kernel/bios32.c
> > index e7ef2b5bea9c..4942cd681e41 100644
> > --- a/arch/arm/kernel/bios32.c
> > +++ b/arch/arm/kernel/bios32.c
> > @@ -471,6 +471,8 @@ static void pcibios_init_hw(struct device *parent, struct hw_pci *hw,
> > bridge->sysdata = sys;
> > bridge->busnr = sys->busnr;
> > bridge->ops = hw->ops;
> > + if (IS_ENABLED(CONFIG_PCI_DOMAINS_GENERIC))
> > + bridge->domain_nr = pci_bus_find_domain_nr(sys, parent);
> >
> > ret = pci_scan_root_bus_bridge(bridge);
> > }
> > diff --git a/arch/arm/mach-dove/pcie.c b/arch/arm/mach-dove/pcie.c
> > index ee91ac6b5ebf..92eb8484b49b 100644
> > --- a/arch/arm/mach-dove/pcie.c
> > +++ b/arch/arm/mach-dove/pcie.c
> > @@ -167,6 +167,8 @@ dove_pcie_scan_bus(int nr, struct pci_host_bridge *bridge)
> > bridge->sysdata = sys;
> > bridge->busnr = sys->busnr;
> > bridge->ops = &pcie_ops;
> > + if (IS_ENABLED(CONFIG_PCI_DOMAINS_GENERIC))
> > + bridge->domain_nr = pci_bus_find_domain_nr(sys, NULL);
>
> The check for CONFIG_PCI_DOMAINS_GENERIC is excessive because there is a
> stub for pci_bus_find_domain_nr().
>
> I'm not an expert in PCI, but maybe the repeated assignment of
> bridge->domain_nr can live in the generic code, say, in
> pci_scan_root_bus_bridge(). E.g. it will set the domain_nr when it is zero.
Yes. There's zero reason h/w drivers should care what the domain_nr is.
There's another issue with domains you should be aware of:
https://lore.kernel.org/linux-pci/20210425152155.mstuxndsoqdbdape@pali/
That may need to be fixed first because deferred probing could cause
the domain to increment each time you retry probe.
Rob
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next prev parent reply other threads:[~2021-05-04 14:37 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-03 14:46 [RFC v2 0/7] PCI: hv: Support host bridge probing on ARM64 Boqun Feng
2021-05-03 14:46 ` [RFC v2 1/7] PCI: Introduce pci_host_bridge::domain_nr Boqun Feng
2021-05-04 5:16 ` Mike Rapoport
2021-05-04 14:34 ` Rob Herring [this message]
2021-05-06 10:52 ` Lorenzo Pieralisi
2021-05-10 13:44 ` Boqun Feng
2021-05-14 9:19 ` Lorenzo Pieralisi
2021-05-03 14:46 ` [RFC v2 2/7] PCI: Allow msi domain set-up at host probing time Boqun Feng
2021-05-03 14:46 ` [RFC v2 3/7] PCI: hv: Generify PCI probing Boqun Feng
2021-05-03 14:46 ` [RFC v2 4/7] PCI: hv: Use pci_host_bridge::domain_nr for PCI domain Boqun Feng
2021-05-03 14:46 ` [RFC v2 5/7] PCI: hv: Set up msi domain at bridge probing time Boqun Feng
2021-05-03 14:46 ` [RFC v2 6/7] PCI: arm64: Allow pci_config_window::parent to be NULL Boqun Feng
2021-05-06 22:25 ` Bjorn Helgaas
2021-05-10 7:04 ` Boqun Feng
2021-05-03 14:46 ` [RFC v2 7/7] PCI: hv: Turn on the host bridge probing on ARM64 Boqun Feng
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