[PATCH v2] of/irq: Ignore interrupt parent for nodes without interrupts

[Ioana Ciornei]

On Fri, Nov 28, 2025 at 06:42:53PM +0200, Ioana Ciornei wrote:
> On Fri, Nov 14, 2025 at 11:47:54AM +0100, Geert Uytterhoeven wrote:
> > The Devicetree Specification states:
> > 
> >     The root of the interrupt tree is determined when traversal of the
> >     interrupt tree reaches an interrupt controller node without an
> >     interrupts property and thus no explicit interrupt parent.
> > 
> > However, of_irq_init() gratuitously assumes that a node without
> > interrupts has an actual interrupt parent if it finds an
> > interrupt-parent property higher up in the device tree.  Hence when such
> > a property is present (e.g. in the root node), the root interrupt
> > controller may not be detected as such, causing a panic:
> > 
> >     OF: of_irq_init: children remain, but no parents
> >     Kernel panic - not syncing: No interrupt controller found.
> > 
> > Commit e91033621d56e055 ("of/irq: Use interrupts-extended to find
> > parent") already fixed a first part, by checking for the presence of an
> > interrupts-extended property.  Fix the second part by only calling
> > of_irq_find_parent() when an interrupts property is present.
> > 
> > Signed-off-by: Geert Uytterhoeven <geert+renesas at glider.be>
> > v2:
> >   - Split off from series "[PATCH/RFC 0/2] of/irq: Fix root interrupt
> >     controller handling"[1] to relax dependencies,
> >   - Drop RFC.
> > 
> > [1] https://lore.kernel.org/all/cover.1759485668.git.geert+renesas@glider.be
> > ---
> >  drivers/of/irq.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/of/irq.c b/drivers/of/irq.c
> > index b174ec29648955c6..5cb1ca89c1d8725d 100644
> > --- a/drivers/of/irq.c
> > +++ b/drivers/of/irq.c
> > @@ -613,7 +613,7 @@ void __init of_irq_init(const struct of_device_id *matches)
> >  		 * are the same distance away from the root irq controller.
> >  		 */
> >  		desc->interrupt_parent = of_parse_phandle(np, "interrupts-extended", 0);
> > -		if (!desc->interrupt_parent)
> > +		if (!desc->interrupt_parent && of_property_present(np, "interrupts"))
> >  			desc->interrupt_parent = of_irq_find_parent(np);
> >  		if (desc->interrupt_parent == np) {
> >  			of_node_put(desc->interrupt_parent);
> > -- 
> > 2.43.0
> > 
> >
> 

Sorry, I somehow removed the verb from the initial email just before
sending it.

s/This change irq-ls-extirq/This change broke irq-ls-extirq

I also fixed it below.

> This change broke irq-ls-extirq and commit 6ba51b7b34ca ("of/irq:
> Handle explicit interrupt parent") does not help with the issue.
> 
> This is how the DT node in lx2160a.dtsi looks like:
> 
> 	extirq: interrupt-controller at 14 {
> 		compatible = "fsl,lx2160a-extirq", "fsl,ls1088a-extirq";
> 		#interrupt-cells = <2>;
> 		#address-cells = <0>;
> 		interrupt-controller;
> 		reg = <0x14 4>;
> 		interrupt-map =
> 			<0 0 &gic GIC_SPI 0 IRQ_TYPE_LEVEL_HIGH>,
> 			<1 0 &gic GIC_SPI 1 IRQ_TYPE_LEVEL_HIGH>,
> 			<2 0 &gic GIC_SPI 2 IRQ_TYPE_LEVEL_HIGH>,
> 			<3 0 &gic GIC_SPI 3 IRQ_TYPE_LEVEL_HIGH>,
> 			<4 0 &gic GIC_SPI 4 IRQ_TYPE_LEVEL_HIGH>,
> 			<5 0 &gic GIC_SPI 5 IRQ_TYPE_LEVEL_HIGH>,
> 			<6 0 &gic GIC_SPI 6 IRQ_TYPE_LEVEL_HIGH>,
> 			<7 0 &gic GIC_SPI 7 IRQ_TYPE_LEVEL_HIGH>,
> 			<8 0 &gic GIC_SPI 8 IRQ_TYPE_LEVEL_HIGH>,
> 			<9 0 &gic GIC_SPI 9 IRQ_TYPE_LEVEL_HIGH>,
> 			<10 0 &gic GIC_SPI 10 IRQ_TYPE_LEVEL_HIGH>,
> 			<11 0 &gic GIC_SPI 11 IRQ_TYPE_LEVEL_HIGH>;
> 		interrupt-map-mask = <0xf 0x0>;
> 	};
> 
> with the following being in the root node:
> 
> 	interrupt-parent = <&gic>;
> 
> Ioana
>