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

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Message-ID: <20180918134152.GA31440@e107981-ln.cambridge.arm.com>
Date:   Tue, 18 Sep 2018 14:41:52 +0100
From:   Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:     Rob Herring <robh+dt@...nel.org>
Cc:     Ray Jui <ray.jui@...adcom.com>, Arnd Bergmann <arnd@...db.de>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Mark Rutland <mark.rutland@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "maintainer:BROADCOM BCM7XXX ARM ARCHITECTURE" 
        <bcm-kernel-feedback-list@...adcom.com>, linux-pci@...r.kernel.org,
        devicetree@...r.kernel.org,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 1/6] PCI: iproc: Update iProc PCI binding for INTx support

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@...adcom.com> wrote:
> > Update the iProc PCIe binding document for better modeling of the legacy
> > interrupt (INTx) support
> >
> > Signed-off-by: Ray Jui <ray.jui@...adcom.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
> >