irqchip/renesas-rzg2l: Fix loss of interrupt

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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: 3fed09559c ("irqchip: Add RZ/G2L IA55 Interrupt Controller driver")
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260818110937.5816-1-biju.das.jz@bp.renesas.com

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Biju Das 2026-08-18 12:09:33 +01:00 • committed by Thomas Gleixner

parent 59e6295fac

commit 50b10bd0c2

1 changed files with 2 additions and 2 deletions

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drivers/irqchip/irq-renesas-rzg2l.c

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