linux-kernel - Re: [PATCH v6 4/5] PCI: add PCI controller for keystone PCIe h/w

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Message-ID: <5467203.eMVRoNeSx1@wuerfel>
Date:	Fri, 18 Jul 2014 21:50:08 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	Rob Herring <robherring2@...il.com>
Cc:	Murali Karicheri <m-karicheri2@...com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Russell King <linux@....linux.org.uk>,
	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <robh+dt@...nel.org>,
	Mohit Kumar <mohit.kumar@...com>,
	Jingoo Han <jg1.han@...sung.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Pratyush Anand <pratyush.anand@...com>,
	Richard Zhu <r65037@...escale.com>,
	Kishon Vijay Abraham I <kishon@...com>,
	Marek Vasut <marex@...x.de>, Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Randy Dunlap <rdunlap@...radead.org>
Subject: Re: [PATCH v6 4/5] PCI: add PCI controller for keystone PCIe h/w

On Friday 18 July 2014 14:31:39 Rob Herring wrote:
> > +
> > + Example:
> > +       pcie_msi_intc: msi-interrupt-controller {
> > +                       interrupt-controller;
> > +                       #interrupt-cells = <1>;
> > +                       interrupt-parent = <&gic>;
> > +                       interrupts = <GIC_SPI 30 IRQ_TYPE_EDGE_RISING>,
> > +                                       <GIC_SPI 31 IRQ_TYPE_EDGE_RISING>,
> > +                                       <GIC_SPI 32 IRQ_TYPE_EDGE_RISING>,
> > +                                       <GIC_SPI 33 IRQ_TYPE_EDGE_RISING>,
> > +                                       <GIC_SPI 34 IRQ_TYPE_EDGE_RISING>,
> > +                                       <GIC_SPI 35 IRQ_TYPE_EDGE_RISING>,
> > +                                       <GIC_SPI 36 IRQ_TYPE_EDGE_RISING>,
> > +                                       <GIC_SPI 37 IRQ_TYPE_EDGE_RISING>;
> > +       };
> > +
> > +pcie_intc: Interrupt controller device node for Legacy irq chip
> > +       interrupt-cells: should be set to 1
> > +       interrupt-parent: Parent interrupt controller phandle
> > +       interrupts: GIC interrupt lines connected to PCI Legacy interrupt lines
> > +
> > + Example:
> > +       pcie_intc: legacy-interrupt-controller {
> > +               interrupt-controller;
> > +               #interrupt-cells = <1>;
> > +               interrupt-parent = <&gic>;
> > +               interrupts = <GIC_SPI 26 IRQ_TYPE_EDGE_RISING>,
> > +                       <GIC_SPI 27 IRQ_TYPE_EDGE_RISING>,
> > +                       <GIC_SPI 28 IRQ_TYPE_EDGE_RISING>,
> > +                       <GIC_SPI 29 IRQ_TYPE_EDGE_RISING>;
> > +       };
> 
> This seems wrong. Legacy interrupts should be described with
> interrupt-map and then PCI child devices have a standard interrupt
> specifier.
> 
> I'm not sure about MSIs, but I would think they would have a standard
> format too.
> 

IIRC, it's actually the correct way to do this here: the problem is that
the PCI IRQs are not directly connected to the GIC, but instead there is
a nested irqchip that has each PCI IRQ routed to it and that requires
an extra EOI for each interrupt.

The interrupt-map in the PCI host points to this special irqchip rather
than to the GIC.

	Arnd
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