[PATCH v2] irqchip: Skip contexts except supervisor in plic_init()

From: Alan Mikhak
Date: Thu Oct 24 2019 - 12:12:04 EST

From: Alan Mikhak <alan.mikhak@xxxxxxxxxx>

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 <alan.mikhak@xxxxxxxxxx>
Acked-by: Paul Walmsley <paul.walmsley@xxxxxxxxxx> # arch/riscv
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
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(parent.np);