Re: [PATCH] PCI: of: Fix MSI domain lookup with child bus nodes

[Rob Herring <robh@kernel.org>]

On Fri, Aug 13, 2021 at 12:19 PM Mauro Carvalho Chehab
<mchehab+huawei@kernel.org> wrote:
>
> Em Fri, 13 Aug 2021 11:02:57 -0500
> Rob Herring <robh@kernel.org> escreveu:
>
> > When a DT contains PCI child bus nodes, lookup of the MSI domain on PCI
> > buses fails resulting in the following warnings:
> >
> > WARNING: CPU: 4 PID: 7 at include/linux/msi.h:256 __pci_enable_msi_range+0x398/0x59c
> >
> > The issue is that pci_host_bridge_of_msi_domain() will check the DT node of
> > the passed in bus even if it's not the host bridge's bus. Based on the
> > name of the function, that's clearly not what we want. Fix this by
> > walking the bus parents to the root bus.
> >
> > Reported-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
> > Cc: Marc Zyngier <maz@kernel.org>
> > Cc: Bjorn Helgaas <bhelgaas@google.com>
> > Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> > Signed-off-by: Rob Herring <robh@kernel.org>
> > ---
> > Compile tested only. Mauro, Can you see if this fixes your issue.
> >
> >  drivers/pci/of.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/drivers/pci/of.c b/drivers/pci/of.c
> > index a143b02b2dcd..ea70aede054c 100644
> > --- a/drivers/pci/of.c
> > +++ b/drivers/pci/of.c
> > @@ -84,6 +84,10 @@ struct irq_domain *pci_host_bridge_of_msi_domain(struct pci_bus *bus)
> >       if (!bus->dev.of_node)
> >               return NULL;
> >
> > +     /* Find the host bridge bus */
> > +     while (!pci_is_root_bus(bus))
> > +             bus = bus->parent;
> > +
> >       /* Start looking for a phandle to an MSI controller. */
> >       d = of_msi_get_domain(&bus->dev, bus->dev.of_node, DOMAIN_BUS_PCI_MSI);
> >       if (d)
>
> Nope, it didn't solve the issue.

Can you try adding some prints of the domain, pci dev, and DT node to
pci_set_bus_msi_domain(). Comparing those when having child nodes or
not would be helpful.

Rob