target/linux/brcm2708/patches-4.19/950-0006-irq-bcm2836-Prevent-spurious-interrupts-and-trap-the.patch

   1 From b46a87040e3d0996bfd76d3c325130fafe76f89a 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 006/773] irq-bcm2836: Prevent spurious interrupts, and trap
   5  them early
   6
   7 The old arch-specific IRQ macros included a dsb to ensure the
   8 write to clear the mailbox interrupt completed before returning
   9 from the interrupt. The BCM2836 irqchip driver needs the same
  10 precaution to avoid spurious interrupts.
  11
  12 Spurious interrupts are still possible for other reasons,
  13 though, so trap them early.
  14 ---
  15  drivers/irqchip/irq-bcm2836.c | 1 +
  16  1 file changed, 1 insertion(+)
  17
  18 --- a/drivers/irqchip/irq-bcm2836.c
  19 +++ b/drivers/irqchip/irq-bcm2836.c
  20 @@ -144,6 +144,7 @@ __exception_irq_entry bcm2836_arm_irqchi
  21                 u32 ipi = ffs(mbox_val) - 1;
  22
  23                 writel(1 << ipi, mailbox0);
  24 +               dsb(sy);
  25                 handle_IPI(ipi, regs);
  26  #endif
  27         } else if (stat) {