From: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Christoph Hellwig <hch@lst.de>,
Bjorn Helgaas <bhelgaas@google.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
"Wesley W. Terpstra" <wesley@sifive.com>,
linux-pci <linux-pci@vger.kernel.org>,
linux-riscv@lists.infradead.org
Subject: Re: [PATCH 1/3] PCI: add a callback to struct pci_host_bridge for adding a new device
Date: Mon, 6 Aug 2018 15:55:54 +0100 [thread overview]
Message-ID: <20180806145554.GE18685@e107981-ln.cambridge.arm.com> (raw)
In-Reply-To: <CAK8P3a0XyK+j4Z+xhxOYKa=5gHmFnWd7=fU=6A3=VkBXxWjSsw@mail.gmail.com>
On Mon, Aug 06, 2018 at 03:54:13PM +0200, Arnd Bergmann wrote:
> On Mon, Aug 6, 2018 at 2:25 PM Christoph Hellwig <hch@lst.de> wrote:
> >
> > On Mon, Aug 06, 2018 at 12:23:10PM +0100, Lorenzo Pieralisi wrote:
> > > > pci_configure_device(dev);
> > > > @@ -2328,6 +2329,11 @@ void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
> > > > ret = pcibios_add_device(dev);
> > > > WARN_ON(ret < 0);
> > > >
> > > > + if (host->add_device) {
> > > > + ret = host->add_device(dev);
> > > > + WARN_ON(ret < 0);
> > > > + }
> > >
> > > This looks fine; we could go a step further and make the hunk above
> > > the default (weak) implementation of pcibios_add_device() that is
> > > currently a NOP returning 0, I will remove it for v4.20.
> >
> > I'd love to see pcibios_add_device go away entirely. But I wonder how to
> > get setup the pci_host_bridge pointer for the remaining architectures that
> > still implement it. I did look for any easy way but couldn't find one.
> > But then I don't really know this area of the PCI code too well.
>
> If the platform doesn't already have a pointer to its pci_host_bridge
> structure, it can call pci_find_host_bridge(bus->dev) to get it.
>
> Ideally, platforms (either arch specific code or drivers/pci/controller)
> should call pci_alloc_host_bridge()/pci_register_host_bridge()
> instead of the traditional pci_create_root_bus() that is less flexible.
> That way, the driver specific structure can get allocated together with
> the host bridge.
Yes that's basically the gist, it should be a matter of identifying code
that creates the root bus (explicitly or implicitly - ie
pci_scan_root_bus()) and patching it up, probably something to be done
(and moved into -next) early -rc* since it is something that can easily
break the world if we miss some code paths. I will have a look into
that and can take this patch for that series if it does not go into
v4.19.
Thanks,
Lorenzo
next prev parent reply other threads:[~2018-08-06 17:05 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-04 10:13 add support for Xilinx PCIe root ports on RISC-V v3 Christoph Hellwig
2018-08-04 10:14 ` [PATCH 1/3] PCI: add a callback to struct pci_host_bridge for adding a new device Christoph Hellwig
2018-08-06 11:23 ` Lorenzo Pieralisi
2018-08-06 12:30 ` Christoph Hellwig
2018-08-06 13:54 ` Arnd Bergmann
2018-08-06 14:55 ` Lorenzo Pieralisi [this message]
2018-08-06 19:49 ` Arnd Bergmann
2018-08-04 10:14 ` [PATCH 2/3] PCI/xilinx: Work-around for hardware DMA limit (32 bits) Christoph Hellwig
2018-08-05 20:02 ` Wesley Terpstra
2018-08-06 12:35 ` Christoph Hellwig
2018-08-06 13:40 ` Lorenzo Pieralisi
2018-08-06 15:33 ` Christoph Hellwig
2018-08-06 16:21 ` Wesley Terpstra
2018-08-06 16:34 ` Christoph Hellwig
2018-08-04 10:14 ` [PATCH 3/3] PCI/xilinx: Depend on OF instead of the ARCH Christoph Hellwig
2018-08-06 10:52 ` Lorenzo Pieralisi
-- strict thread matches above, loose matches on Subject: below --
2018-08-01 15:14 add support for Xilinx PCIe root ports on RISC-V v2 Christoph Hellwig
2018-08-01 15:14 ` [PATCH 1/3] PCI: add a callback to struct pci_host_bridge for adding a new device Christoph Hellwig
2018-08-02 16:54 ` Lorenzo Pieralisi
2018-08-04 10:11 ` Christoph Hellwig
2018-08-15 19:52 ` Bjorn Helgaas
2018-08-16 20:59 ` Bjorn Helgaas
2018-08-16 21:04 ` Arnd Bergmann
2018-08-17 15:25 ` Lorenzo Pieralisi
2018-08-17 15:47 ` Arnd Bergmann
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