--- a/drivers/gpio/gpio-realtek-otto.c
+++ b/drivers/gpio/gpio-realtek-otto.c
@@ -304,6 +304,7 @@ static int realtek_gpio_irq_set_affinity
 static int realtek_gpio_irq_init(struct gpio_chip *gc)
 {
 	struct realtek_gpio_ctrl *ctrl = gpiochip_get_data(gc);
+	void __iomem *irq_cpu_mask;
 	unsigned int port;
 	int cpu;
 
@@ -311,8 +312,16 @@ static int realtek_gpio_irq_init(struct
 		realtek_gpio_write_imr(ctrl, port, 0, 0);
 		realtek_gpio_clear_isr(ctrl, port, GENMASK(7, 0));
 
-		for_each_cpu(cpu, &ctrl->cpu_irq_maskable)
-			iowrite8(GENMASK(7, 0), realtek_gpio_irq_cpu_mask(ctrl, port, cpu));
+		/*
+		 * Uniprocessor builds assume a mask always contains one CPU,
+		 * so only start the loop if we have at least one maskable CPU.
+		 */
+		if(!cpumask_empty(&ctrl->cpu_irq_maskable)) {
+			for_each_cpu(cpu, &ctrl->cpu_irq_maskable) {
+				irq_cpu_mask = realtek_gpio_irq_cpu_mask(ctrl, port, cpu);
+				iowrite8(GENMASK(7, 0), irq_cpu_mask);
+			}
+		}
 	}
 
 	return 0;