On Wed, Aug 15, 2018 at 02:52:28PM -0500, Bjorn Helgaas wrote:
> On Thu, Aug 02, 2018 at 05:54:30PM +0100, Lorenzo Pieralisi wrote:
> > On Wed, Aug 01, 2018 at 05:14:01PM +0200, Christoph Hellwig wrote:
> > > There is currently no way for a PCIe bridge to impose constraints on
> > > devices added to it. For example, the Xilinx PCIe host bridge only
> > > supports 32-bit physical addresses (due to a limitation on the AXI
> > > port's address width). Thus, even devices that claim to support 64-bit
> > > DMA addresses must be restricted to 32-bit addresses when attached to
> > > this host controller.
> > >
> > > This patch adds a "add_dev" method to struct pci_host_bridge that
> > > allows the host driver to act upon acting adding devices.
> > >
> > > Based on an earlier patch from Wesley W. Terpstra <wesley@xxxxxxxxxx>.
> > >
> > > Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> > > ---
> > > drivers/pci/probe.c | 4 ++++
> > > include/linux/pci.h | 1 +
> > > 2 files changed, 5 insertions(+)
> > >
> > > diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> > > index ac876e32de4b..8736d78ffc66 100644
> > > --- a/drivers/pci/probe.c
> > > +++ b/drivers/pci/probe.c
> > > @@ -2290,6 +2290,7 @@ static void pci_set_msi_domain(struct pci_dev *dev)
> > >
> > > void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
> > > {
> > > + struct pci_host_bridge *host = pci_find_host_bridge(bus);
> > > int ret;
> > >
> > > pci_configure_device(dev);
> > > @@ -2331,6 +2332,9 @@ void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
> > > /* Set up MSI IRQ domain */
> > > pci_set_msi_domain(dev);
> > >
> > > + if (host->add_dev)
> > > + host->add_dev(dev);
> >
> > Hi Christoph,
> >
> > while at it, IMHO it would be good to match the current
> > pcibios_add_device() prototype (ie returning an int error value)
> > so that this change can pave the way to removing yet another
> > pcibios call.
> >
> > Actually we could make pcibios_add_device() removal as part of this
> > series but you would have to patch all related host bridge drivers
> > initializations so I am happy for this patch to go standalone (I can
> > patch the rest of the code) - I leave it to Bjorn's decision.
>
> This patch seems OK to me.
>
> I don't really care about the prototype. There's only one
> pcibios_add_device() implementation (x86) that returns anything other
> than 0, and that's a pretty obscure error case related to f9a37be0f02a
> ("x86: Use PCI setup data"), which lets us use ROM data from boot
> services. Even then the only thing that happens is a WARN_ON(). A
> more descriptive printk would be a lot more useful.
Thinking about this some more, I'm not so sure about the connection
with removing pcibios_add_device(). This host_bridge->add_dev() hook
would be for host bridge-specific things, while pcibios_add_device()
is for arch-specific things.
I'd still love to get rid of pcibios_add_device() (especially the
non-arch-specific things like the pci_claim_resource() in s390); I'm
just not sure yet whether this particular patch is the vehicle.
