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

[Ioana Ciornei]

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
> 
>

This change 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