Re: [PATCH 03/15] PCI: mvebu: Check that PCI bridge specified in DT has function number zero

Bjorn Helgaas
2022-01-07T18:15:19Z

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?

> 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
>