Re: [PATCH 1/6] PCI: iproc: Update iProc PCI binding for INTx support

Lorenzo Pieralisi
2018-09-18T13:42:03Z

On Mon, Jun 04, 2018 at 09:17:49AM -0500, Rob Herring wrote:
> +Arnd
>
> On Tue, May 29, 2018 at 4:58 PM, Ray Jui <ray.jui@broadcom.com> wrote:
> > Update the iProc PCIe binding document for better modeling of the legacy
> > interrupt (INTx) support
> >
> > Signed-off-by: Ray Jui <ray.jui@broadcom.com>
> > ---
> > .../devicetree/bindings/pci/brcm,iproc-pcie.txt | 31 +++++++++++++++++-----
> > 1 file changed, 24 insertions(+), 7 deletions(-)
> >
> > diff --git a/Documentation/devicetree/bindings/pci/brcm,iproc-pcie.txt b/Documentation/devicetree/bindings/pci/brcm,iproc-pcie.txt
> > index b8e48b4..7ea24dc 100644
> > --- a/Documentation/devicetree/bindings/pci/brcm,iproc-pcie.txt
> > +++ b/Documentation/devicetree/bindings/pci/brcm,iproc-pcie.txt
> > @@ -13,9 +13,6 @@ controller, used in Stingray
> > PAXB-based root complex is used for external endpoint devices. PAXC-based
> > root complex is connected to emulated endpoint devices internal to the ASIC
> > - reg: base address and length of the PCIe controller I/O register space
> > -- #interrupt-cells: set to <1>
> > -- interrupt-map-mask and interrupt-map, standard PCI properties to define the
> > - mapping of the PCIe interface to interrupt numbers
> > - linux,pci-domain: PCI domain ID. Should be unique for each host controller
> > - bus-range: PCI bus numbers covered
> > - #address-cells: set to <3>
> > @@ -41,6 +38,16 @@ Required:
> > - brcm,pcie-ob-axi-offset: The offset from the AXI address to the internal
> > address used by the iProc PCIe core (not the PCIe address)
> >
> > +Legacy interrupt (INTx) support (optional):
> > +
> > +Note INTx is for PAXB only.
> > +
> > +- interrupt-controller: claims itself as an interrupt controller for INTx
> > +- #interrupt-cells: set to <1>
> > +- interrupt-map-mask and interrupt-map, standard PCI properties to define
> > +the mapping of the PCIe interface to interrupt numbers
> > +- interrupts: interrupt line wired to the generic GIC for INTx support
> > +
> > MSI support (optional):
> >
> > For older platforms without MSI integrated in the GIC, iProc PCIe core provides
> > @@ -77,9 +84,14 @@ Example:
> > compatible = "brcm,iproc-pcie";
> > reg = <0x18012000 0x1000>;
> >
> > + interrupt-controller;
> > #interrupt-cells = <1>;
> > - interrupt-map-mask = <0 0 0 0>;
> > - interrupt-map = <0 0 0 0 &gic GIC_SPI 100 IRQ_TYPE_NONE>;
> > + interrupt-map-mask = <0 0 0 7>;
> > + interrupt-map = <0 0 0 1 &pcie0 1>,
>
> Are you sure this works? The irq parsing code will ignore
> interrupt-map if interrupt-controller is found. In other words, you
> should have one or the other, but not both.
>
> Maybe it happens to work because "pcie0" is this node and your irq
> numbers are the same.
>
> Arnd, any thoughts on this?

To start with, I think the destination IRQ number is wrong, what the
mappings actually do is mapping the PCI interrupt line (ie #INTA, #INTB,
#INTC, #INTD) to input {0,1,2,3} of the PCI host bridge (pseudo)
interrupt controller.

I really want to clean this up since currently there are different
DT bindings defining this in different ways which resulted in
non-consistent kernel code.

AFAICS, the Aardvark PCIe controller bindings define the mapping
as I expect:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/pci/aardvark-pci.txt?h=v4.19-rc4

but I would like to get Rob and Arnd viewpoint on this so that
we can close this topic once for all.

Cheers,
Lorenzo

>
> > + <0 0 0 2 &pcie0 2>,
> > + <0 0 0 3 &pcie0 3>,
> > + <0 0 0 4 &pcie0 4>;
> > + interrupts = <GIC_SPI 100 IRQ_TYPE_NONE>;
> >
> > linux,pci-domain = <0>;
> >
> > @@ -115,9 +127,14 @@ Example:
> > compatible = "brcm,iproc-pcie";
> > reg = <0x18013000 0x1000>;
> >
> > + interrupt-controller;
> > #interrupt-cells = <1>;
> > - interrupt-map-mask = <0 0 0 0>;
> > - interrupt-map = <0 0 0 0 &gic GIC_SPI 106 IRQ_TYPE_NONE>;
> > + interrupt-map-mask = <0 0 0 7>;
> > + interrupt-map = <0 0 0 1 &pcie1 1>,
> > + <0 0 0 2 &pcie1 2>,
> > + <0 0 0 3 &pcie1 3>,
> > + <0 0 0 4 &pcie1 4>;
> > + interrupts = <GIC_SPI 106 IRQ_TYPE_NONE>;
> >
> > linux,pci-domain = <1>;
> >
> > --
> > 2.1.4
> >