irqchip/qcom: Fix check for spurious interrupts

When the interrupts for a combiner span multiple registers it must be
checked if any interrupts have been asserted on each register before
checking for spurious interrupts.

Checking each register seperately leads to false positive warnings.

[ tglx: Massaged changelog ]

Fixes: f20cc9b ("irqchip/qcom: Add IRQ combiner driver")
Signed-off-by: Agustin Vega-Frias <agustinv@codeaurora.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: timur@codeaurora.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/1525184090-26143-1-git-send-email-agustinv@codeaurora.org

drivers/irqchip/qcom-irq-combiner.c

@@ -1,4 +1,4 @@
-/* Copyright (c) 2015-2016, The Linux Foundation. All rights reserved.
+/* Copyright (c) 2015-2018, The Linux Foundation. All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 and
@@ -68,7 +68,7 @@ static void combiner_handle_irq(struct irq_desc *desc)
 
 		bit = readl_relaxed(combiner->regs[reg].addr);
 		status = bit & combiner->regs[reg].enabled;
-		if (!status)
+		if (bit && !status)
 			pr_warn_ratelimited("Unexpected IRQ on CPU%d: (%08x %08lx %p)\n",
 					    smp_processor_id(), bit,
 					    combiner->regs[reg].enabled,