linux-kernel - [PATCH 3/3] irqchip: renesas-rzg2l: Fix irq storm with edge trigger detection for TINT

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Date:   Mon, 18 Sep 2023 13:24:11 +0100
From:   Biju Das <biju.das.jz@...renesas.com>
To:     Thomas Gleixner <tglx@...utronix.de>, Marc Zyngier <maz@...nel.org>
Cc:     Biju Das <biju.das.jz@...renesas.com>,
        Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
        Claudiu Beznea <claudiu.beznea.uj@...renesas.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Biju Das <biju.das.au@...il.com>, linux-kernel@...r.kernel.org,
        linux-renesas-soc@...r.kernel.org
Subject: [PATCH 3/3] irqchip: renesas-rzg2l: Fix irq storm with edge trigger detection for TINT

In case of edge trigger detection, enabling the TINT source causes a
phantum interrupt that leads to irq storm. So clear the phantum interrupt
in rzg2l_irqc_irq_enable().

This issue is observed when the irq handler disables the interrupts using
disable_irq_nosync() and scheduling a work queue and in the work queue,
re-enabling the interrupt with enable_irq().

Fixes: 3fed09559cd8 ("irqchip: Add RZ/G2L IA55 Interrupt Controller driver")
Signed-off-by: Biju Das <biju.das.jz@...renesas.com>
Tested-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
---
 drivers/irqchip/irq-renesas-rzg2l.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/irqchip/irq-renesas-rzg2l.c b/drivers/irqchip/irq-renesas-rzg2l.c
index 33a22bafedcd..78a9e90512a6 100644
--- a/drivers/irqchip/irq-renesas-rzg2l.c
+++ b/drivers/irqchip/irq-renesas-rzg2l.c
@@ -144,6 +144,12 @@ static void rzg2l_irqc_irq_enable(struct irq_data *d)
 		reg = readl_relaxed(priv->base + TSSR(tssr_index));
 		reg |= (TIEN | tint) << TSSEL_SHIFT(tssr_offset);
 		writel_relaxed(reg, priv->base + TSSR(tssr_index));
+		/*
+		 * In case of edge trigger detection, enabling the TINT source
+		 * cause a phantum interrupt that leads to irq storm. So clear
+		 * the phantum interrupt.
+		 */
+		rzg2l_tint_eoi(d);
 		raw_spin_unlock(&priv->lock);
 		irq_chip_unmask_parent(d);
 	}
-- 
2.25.1