From 50b10bd0c2d721ad38abd1abe3acdefb6caa0944 Mon Sep 17 00:00:00 2001 From: Biju Das Date: Tue, 18 Aug 2026 12:09:33 +0100 Subject: [PATCH] irqchip/renesas-rzg2l: Fix loss of interrupt rzg2l_clear_irq_int() and rzg2l_clear_tint_int() perform a read-modify-write on the ISCR/TSCR status registers to clear the bit for the interrupt just handled. Since these registers are write-0-to-clear per bit, this is racy: If another interrupt's status bit gets set between the read and the write, that bit is written back as 0 by the software-constructed value, clearing an interrupt that hasn't been serviced yet and losing it. This can be reproduced by triggering multiple interrupts at once, e.g.: gpioset -c gpiochip0 355=0 353=0 328=0 352=0 Fix this by writing back only the bit being cleared, with all other bits set to 1, instead of read-modify-writing the whole register. Since 1-bits are left unchanged by hardware, concurrently-set status bits for other interrupts are preserved. Fixes: 3fed09559cd8 ("irqchip: Add RZ/G2L IA55 Interrupt Controller driver") Signed-off-by: Biju Das Signed-off-by: Thomas Gleixner Link: https://patch.msgid.link/20260818110937.5816-1-biju.das.jz@bp.renesas.com --- drivers/irqchip/irq-renesas-rzg2l.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/irqchip/irq-renesas-rzg2l.c b/drivers/irqchip/irq-renesas-rzg2l.c index f6b2e69a2f4e..b3774f82855a 100644 --- a/drivers/irqchip/irq-renesas-rzg2l.c +++ b/drivers/irqchip/irq-renesas-rzg2l.c @@ -161,7 +161,7 @@ static void rzg2l_clear_irq_int(struct rzg2l_irqc_priv *priv, unsigned int hwirq * falling/rising-edge. */ if ((iscr & bit) && (iitsr & IITSR_IITSEL_MASK(hw_irq))) { - writel_relaxed(iscr & ~bit, priv->base + ISCR); + writel_relaxed(~bit, priv->base + ISCR); /* * Enforce that the posted write is flushed to prevent that the * just handled interrupt is raised again. @@ -177,7 +177,7 @@ static void rzg2l_clear_tint_int(struct rzg2l_irqc_priv *priv, unsigned int hwir reg = readl_relaxed(priv->base + TSCR); if (reg & bit) { - writel_relaxed(reg & ~bit, priv->base + TSCR); + writel_relaxed(~bit, priv->base + TSCR); /* * Enforce that the posted write is flushed to prevent that the * just handled interrupt is raised again.