# \[PATCH v2\] irqchip/bcm2836: Prevent spurious interrupts

- From: Eric Anholt \<hidden\>
- Date: 2016-10-27 18:21:05 
- List: linux-arm-kernel
- Page: https://ratatoskr.run/linux-arm-kernel/2016/10/4863306
- Thread: https://ratatoskr.run/linux-arm-kernel/2016/10/4863306/t.md

```text
From: Phil Elwell <redacted>

The old arch-specific IRQ macros included a dsb to ensure the
write to clear the mailbox interrupt completed before returning
from the interrupt. The BCM2836 irqchip driver needs the same
precaution to avoid spurious interrupts.

Signed-off-by: Phil Elwell <redacted>
Signed-off-by: Eric Anholt <redacted>
---
 drivers/irqchip/irq-bcm2836.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/irqchip/irq-bcm2836.c b/drivers/irqchip/irq-bcm2836.c
index d96b2c947e74..93e3f7660c42 100644
--- a/drivers/irqchip/irq-bcm2836.c
+++ b/drivers/irqchip/irq-bcm2836.c
@@ -175,6 +175,7 @@ __exception_irq_entry bcm2836_arm_irqchip_handle_irq(struct pt_regs *regs)
 		u32 ipi = ffs(mbox_val) - 1;
 
 		writel(1 << ipi, mailbox0);
+		dsb(sy);
 		handle_IPI(ipi, regs);
 #endif
 	} else if (stat) {
-- 
2.9.3
```