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SubjectRe: [PATCH 1/2] of_pci_irq: add a check to fallback to standard device tree parsing
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On Wed, 2018-01-31 at 10:02 -0600, Rob Herring wrote:
> On Wed, Jan 31, 2018 at 1:41 AM, Ryder Lee <ryder.lee@mediatek.com> wrote:
> > A root complex usually consist of a host bridge and multiple P2P bridges,
> > and someone may express that in the form of a root node with many subnodes
> > and list all four interrupts for each slot (child node) in the root node
> > like this:
> >
> > pcie-controller {
> > ...
> > interrupt-map-mask = <0xf800 0 0 7>;
> > interrupt-map = <0x0000 0 0 {INTx} &{interrupt parent} ...>
> > 0x0800 0 0 {INTx} &{interrupt parent} ...>;
> >
> > pcie@0,0 {
> > reg = <0x0000 0 0 0 0>;
> > ...
> > };
> >
> > pcie@1,0 {
> > reg = <0x0800 0 0 0 0>;
> > ...
> > };
> > };
> >
> > As shown above, we'd like to propagate IRQs from a root port to the devices
> > in the hierarchy below it in this way. However, it seems that the current
> > parser couldn't handle such cases and will get something unexpected below:
> >
> > pcieport 0000:00:01.0: assign IRQ: got 213
> > igb 0000:01:00.0: assign IRQ: got 212
> >
> > There is a device which is connected to 2nd slot, but the port doesn't share
> > the same IRQ with its downstream devices. The problem here is that, if the
> > loop found a P2P bridge, it wouldn't check whether the reg property exists
> > in ppnode or not but just pass the subordinate devfn to of_irq_parse_raw(),
> > thus the subsequent flow couldn't correctly resolve them.
> >
> > Fix this by adding a check to fallback to standard device tree parsing.
> >
> > Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
> > ---
> > Please refer to the previous discussion thread: https://patchwork.ozlabs.org/patch/829108/
> > ---
> > drivers/of/of_pci_irq.c | 14 ++++++++++++--
> > 1 file changed, 12 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/of/of_pci_irq.c b/drivers/of/of_pci_irq.c
> > index 3a05568..e445866 100644
> > --- a/drivers/of/of_pci_irq.c
> > +++ b/drivers/of/of_pci_irq.c
> > @@ -86,8 +86,18 @@ int of_irq_parse_pci(const struct pci_dev *pdev, struct of_phandle_args *out_irq
> > out_irq->np = ppnode;
> > out_irq->args_count = 1;
> > out_irq->args[0] = pin;
> > - laddr[0] = cpu_to_be32((pdev->bus->number << 16) | (pdev->devfn << 8));
> > - laddr[1] = laddr[2] = cpu_to_be32(0);
> > +
> > + if (!dn && ppnode) {
>
> I would think whether you have a child device in DT or not is
> irrelevant. If it's the bridge address you need to look at for
> resolving interrupts, that would be true regardless.
>
> > + const __be32 *addr;
> > +
> > + addr = of_get_property(ppnode, "reg", NULL);
> > + if (addr)
> > + memcpy(laddr, addr, 3);
>
> Can't you just adjust pdev to be ppdev in this case and then use the
> existing code to set laddr?

Okay, I will try it out and and see if the code gets better or worse.

> Please copy the powerpc list on this. I worry that touching this
> function will break something.
> BTW, this code is moving to drivers/pci/ in 4.16.

Sure. I will loop more people in next version.

Thanks

> _______________________________________________
> Linux-mediatek mailing list
> Linux-mediatek@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-mediatek


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