Messages in this thread | | | Date | Fri, 7 Jan 2022 19:18:19 +0100 | From | Pali Rohár <> | Subject | Re: [PATCH 03/15] PCI: mvebu: Check that PCI bridge specified in DT has function number zero |
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On Friday 07 January 2022 12:15:12 Bjorn Helgaas wrote: > On Thu, Nov 25, 2021 at 01:45:53PM +0100, Pali Rohár wrote: > > Driver cannot handle PCI bridges at non-zero function address. So add > > appropriate check. Currently all in-tree kernel DTS files set PCI bridge > > function to zero. > > Why can the driver not handle bridges at non-zero function addresses? > The PCI spec allows that, doesn't it? Is this a hardware limitation?
It is software / kernel limitation.
Because this bridge is virtual, emulated by pci-bridge-emul.c driver and this driver can emulate only single function PCI-to-PCI bridge device.
> > Signed-off-by: Pali Rohár <pali@kernel.org> > > Cc: stable@vger.kernel.org > > --- > > drivers/pci/controller/pci-mvebu.c | 5 +++++ > > 1 file changed, 5 insertions(+) > > > > diff --git a/drivers/pci/controller/pci-mvebu.c b/drivers/pci/controller/pci-mvebu.c > > index 6197f7e7c317..08274132cdfb 100644 > > --- a/drivers/pci/controller/pci-mvebu.c > > +++ b/drivers/pci/controller/pci-mvebu.c > > @@ -864,6 +864,11 @@ static int mvebu_pcie_parse_port(struct mvebu_pcie *pcie, > > port->devfn = of_pci_get_devfn(child); > > if (port->devfn < 0) > > goto skip; > > + if (PCI_FUNC(port->devfn) != 0) { > > + dev_err(dev, "%s: invalid function number, must be zero\n", > > + port->name); > > + goto skip; > > + } > > > > ret = mvebu_get_tgt_attr(dev->of_node, port->devfn, IORESOURCE_MEM, > > &port->mem_target, &port->mem_attr); > > -- > > 2.20.1 > >
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