irqchip/renesas-rzv2h: Prevent TINT spurious interrupt

A spurious TINT interrupt is seen during boot on RZ/G3E SMARC EVK.

A glitch in the edge detection circuit can cause a spurious interrupt.

Clear the status flag after setting the ICU_TSSRk registers, which is
recommended in the hardware manual as a countermeasure.

Fixes: 0d7605e ("irqchip: Add RZ/V2H(P) Interrupt Control Unit (ICU) driver")
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org

Author: bijudas

drivers/irqchip/irq-renesas-rzv2h.c

@@ -170,6 +170,14 @@ static void rzv2h_tint_irq_endisable(struct irq_data *d, bool enable)
 	else
 		tssr &= ~ICU_TSSR_TIEN(tssel_n, priv->info->field_width);
 	writel_relaxed(tssr, priv->base + priv->info->t_offs + ICU_TSSR(k));
+
+	/*
+	 * A glitch in the edge detection circuit can cause a spurious
+	 * interrupt. Clear the status flag after setting the ICU_TSSRk
+	 * registers, which is recommended by the hardware manual as a
+	 * countermeasure.
+	 */
+	writel_relaxed(BIT(tint_nr), priv->base + priv->info->t_offs + ICU_TSCLR);
 }
 
 static void rzv2h_icu_irq_disable(struct irq_data *d)