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* [PATCH v2] irqchip: Skip contexts except supervisor in plic_init()
@ 2019-10-24 16:11 Alan Mikhak
  0 siblings, 0 replies; only message in thread
From: Alan Mikhak @ 2019-10-24 16:11 UTC (permalink / raw)
  To: linux-kernel, linux-riscv, tglx, jason, maz, palmer, paul.walmsley
  Cc: Alan Mikhak

From: Alan Mikhak <>

Modify plic_init() to skip .dts interrupt contexts other
than supervisor external interrupt.

The .dts entry for plic may specify multiple interrupt contexts.
For example, it may assign two entries IRQ_M_EXT and IRQ_S_EXT,
in that order, to the same interrupt controller. This patch
modifies plic_init() to skip the IRQ_M_EXT context since
IRQ_S_EXT is currently the only supported context.

If IRQ_M_EXT is not skipped, plic_init() will report "handler
already present for context" when it comes across the IRQ_S_EXT
context in the next iteration of its loop.

Without this patch, .dts would have to be edited to replace the
value of IRQ_M_EXT with -1 for it to be skipped.

Signed-off-by: Alan Mikhak <>
Acked-by: Paul Walmsley <> # arch/riscv
Reviewed-by: Christoph Hellwig <>
 drivers/irqchip/irq-sifive-plic.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
index c72c036aea76..5f2a773d5669 100644
--- a/drivers/irqchip/irq-sifive-plic.c
+++ b/drivers/irqchip/irq-sifive-plic.c
@@ -251,8 +251,8 @@ static int __init plic_init(struct device_node *node,
-		/* skip context holes */
-		if (parent.args[0] == -1)
+		/* skip contexts other than supervisor external interrupt */
+		if (parent.args[0] != IRQ_S_EXT)
 		hartid = plic_find_hart_id(;

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2019-10-24 16:11 [PATCH v2] irqchip: Skip contexts except supervisor in plic_init() Alan Mikhak

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