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

[Jon Hunter]

On 19/11/2025 08:53, Geert Uytterhoeven wrote:
> On Tue, 18 Nov 2025 at 20:55, Krzysztof Kozlowski <krzk at kernel.org> wrote:
>> On 18/11/2025 20:34, Mark Brown 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:
>>>
>>> I'm seeing a boot regression on the TI x15 platform in -next which
>>> bisects to this patch in -next, unfortunately even with earlycon (though
>>> just earlycon, I don't know the platform specific runes) the board just
>>> dies with no output:
>>>
>>>    https://validation.linaro.org/scheduler/job/4252918#L409
>>>
>>> It does seem like a plausible patch for this sort of issue though, and
>>> the bisect converges smoothly:
>>
>> All Samsung platforms fail as well. I was waiting with bisection but
>> Marek was as usually very fast:
>>
>> https://lore.kernel.org/all/20251118115037.1866871-1-m.szyprowski@samsung.com/
> 
> Yeah, the various ti,omap[45]-wugen-mpu nodes have interrupt-parent
> properties, but no interrupts{-extended} properties.
> 
> Does the following (whitespace-damaged) patch, to restore finding an
> explicit interrupt-parent, fix the issue?
> 
> --- a/drivers/of/irq.c
> +++ b/drivers/of/irq.c
> @@ -685,6 +685,8 @@ void __init of_irq_init(const struct of_device_id *matches)
>                  desc->interrupt_parent = of_parse_phandle(np,
> "interrupts-extended", 0);
>                  if (!desc->interrupt_parent && of_property_present(np,
> "interrupts"))
>                          desc->interrupt_parent = of_irq_find_parent(np);
> +               if (!desc->interrupt_parent)
> +                       desc->interrupt_parent = of_parse_phandle(np,
> "interrupt-parent", 0);
>                  if (desc->interrupt_parent == np) {
>                          of_node_put(desc->interrupt_parent);
>                          desc->interrupt_parent = NULL;


This patch also breaks various Tegra boards but the above does fix it.

Jon	

-- 
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