linux-kernel - [PATCH v2] irqchip: Skip contexts except supervisor in plic

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Message-Id: <1571933503-21504-1-git-send-email-alan.mikhak@sifive.com>
Date:   Thu, 24 Oct 2019 09:11:43 -0700
From:   Alan Mikhak <alan.mikhak@...ive.com>
To:     linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org,
        tglx@...utronix.de, jason@...edaemon.net, maz@...nel.org,
        palmer@...ive.com, paul.walmsley@...ive.com
Cc:     Alan Mikhak <alan.mikhak@...ive.com>
Subject: [PATCH v2] irqchip: Skip contexts except supervisor in plic_init()

From: Alan Mikhak <alan.mikhak@...ive.com>

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@...ive.com>
Acked-by: Paul Walmsley <paul.walmsley@...ive.com> # arch/riscv
Reviewed-by: Christoph Hellwig <hch@....de>
---
 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,
 			continue;
 		}

-		/* skip context holes */
-		if (parent.args[0] == -1)
+		/* skip contexts other than supervisor external interrupt */
+		if (parent.args[0] != IRQ_S_EXT)
 			continue;

 		hartid = plic_find_hart_id(parent.np);
-- 
2.7.4