target/linux/brcm2708/patches-4.4/0005-irq-bcm2836-Prevent-spurious-interrupts-and-trap-the.patch

   1 From 640ebb7ef07930c2f22362cadf8bfc3e46064dc0 Mon Sep 17 00:00:00 2001
   2 From: Phil Elwell <phil@raspberrypi.org>
   3 Date: Fri, 4 Dec 2015 17:41:50 +0000
   4 Subject: [PATCH] irq-bcm2836: Prevent spurious interrupts, and trap them early
   5
   6 The old arch-specific IRQ macros included a dsb to ensure the
   7 write to clear the mailbox interrupt completed before returning
   8 from the interrupt. The BCM2836 irqchip driver needs the same
   9 precaution to avoid spurious interrupts.
  10
  11 Spurious interrupts are still possible for other reasons,
  12 though, so trap them early.
  13 ---
  14  drivers/irqchip/irq-bcm2836.c | 3 ++-
  15  1 file changed, 2 insertions(+), 1 deletion(-)
  16
  17 --- a/drivers/irqchip/irq-bcm2836.c
  18 +++ b/drivers/irqchip/irq-bcm2836.c
  19 @@ -170,9 +170,10 @@ __exception_irq_entry bcm2836_arm_irqchi
  20                 u32 ipi = ffs(mbox_val) - 1;
  21
  22                 writel(1 << ipi, mailbox0);
  23 +               dsb();
  24                 handle_IPI(ipi, regs);
  25  #endif
  26 -       } else {
  27 +       } else if (stat) {
  28                 u32 hwirq = ffs(stat) - 1;
  29
  30                 handle_IRQ(irq_linear_revmap(intc.domain, hwirq), regs);