From: Phil Elwell <phil@raspberrypi.org>
Date: Fri, 4 Dec 2015 17:41:50 +0000 (+0000)
Subject: irq-bcm2836: Prevent spurious interrupts, and trap them early
X-Git-Tag: archive/raspbian/4.9.13-1+rpi1~9^2~196
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=71069bc740f638495eb33d6db6a281b5fa697657;p=linux-4.9.git

irq-bcm2836: Prevent spurious interrupts, and trap them early

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.

Spurious interrupts are still possible for other reasons,
though, so trap them early.
---

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) {