From e91033621d56e055803c4c4ba507fbbb2d145a7f Mon Sep 17 00:00:00 2001 From: Samuel Holland Date: Tue, 12 Apr 2022 00:15:28 -0500 Subject: of/irq: Use interrupts-extended to find parent The RISC-V PLIC binding uses interrupts-extended to specify its parent domain(s). That binding does not allow the interrupt-parent property to appear in the irqchip node. This prevents of_irq_init from properly detecting the irqchip hierarchy. If no interrupt-parent property is present in the enclosing bus or root node, then desc->interrupt_parent will be NULL for both the per-CPU RISC-V INTC (the actual root domain) and the RISC-V PLIC. Similarly, if the bus or root node specifies `interrupt-parent = <&plic>`, then of_irq_init will hit the `desc->interrupt_parent == np` check, and again all parents will be NULL. So things happen to work today for some boards due to Makefile ordering. However, things break when another irqchip ("foo") is stacked on top of the PLIC. The bus or root node will have `interrupt-parent = <&foo>`, since that is what all of the other peripherals need. When of_irq_init runs, it will try to find the PLIC's parent domain. of_irq_find_parent will fall back to using the interrupt-parent property of the PLIC's parent node (i.e. the bus or root node), and of_irq_init will see "foo" as the PLIC's parent domain. But this is wrong, because "foo" is actually the PLIC's child domain! So of_irq_init wrongly attempts to init the stacked irqchip before the PLIC. This fails and breaks booting. Fix this by using the first node referenced by interrupts-extended as the parent when that property is present. This allows of_irq_init to see the relationship between the PLIC and the per-CPU RISC-V INTC, and thus only the RISC-V INTC is (correctly) considered a root domain. Signed-off-by: Samuel Holland Signed-off-by: Rob Herring Link: https://lore.kernel.org/r/20220412051529.6293-1-samuel@sholland.org --- drivers/of/irq.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) (limited to 'drivers/of') diff --git a/drivers/of/irq.c b/drivers/of/irq.c index 2b07677a386b..aa485eb312ac 100644 --- a/drivers/of/irq.c +++ b/drivers/of/irq.c @@ -550,9 +550,18 @@ void __init of_irq_init(const struct of_device_id *matches) desc->irq_init_cb = match->data; desc->dev = of_node_get(np); - desc->interrupt_parent = of_irq_find_parent(np); - if (desc->interrupt_parent == np) + /* + * interrupts-extended can reference multiple parent domains. + * Arbitrarily pick the first one; assume any other parents + * are the same distance away from the root irq controller. + */ + desc->interrupt_parent = of_parse_phandle(np, "interrupts-extended", 0); + if (!desc->interrupt_parent) + desc->interrupt_parent = of_irq_find_parent(np); + if (desc->interrupt_parent == np) { + of_node_put(desc->interrupt_parent); desc->interrupt_parent = NULL; + } list_add_tail(&desc->list, &intc_desc_list); } -- cgit v1.2.3