gpio: pca953x: fix IRQ storm on system wake up

[ Upstream commit 3e38f946062b4845961ab86b726651b4457b2af8 ]

If an input changes state during wake-up and is used as an interrupt
source, the IRQ handler reads the volatile input register to clear the
interrupt mask and deassert the IRQ line. However, the IRQ handler is
triggered before access to the register is granted, causing the read
operation to fail.

As a result, the IRQ handler enters a loop, repeatedly printing the
"failed reading register" message, until `pca953x_resume()` is eventually
called, which restores the driver context and enables access to
registers.

Fix by disabling the IRQ line before entering suspend mode, and
re-enabling it after the driver context is restored in `pca953x_resume()`.

An IRQ can be disabled with disable_irq() and still wake the system as
long as the IRQ has wake enabled, so the wake-up functionality is
preserved.

Fixes: b76574300504 ("gpio: pca953x: Restore registers after suspend/resume cycle")
Cc: stable@vger.kernel.org
Signed-off-by: Emanuele Ghidoli <emanuele.ghidoli@toradex.com>
Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20250512095441.31645-1-francesco@dolcini.it
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c
index a39c8ebd410e4e44059685c8e19224afc3081fc7..faadbe66b23e71b1ee1e912c0adbbcc8bef0c2b1 100644 (file)
--- a/drivers/gpio/gpio-pca953x.c
+++ b/drivers/gpio/gpio-pca953x.c
@@ -1209,6 +1209,8 @@ static int pca953x_restore_context(struct pca953x_chip *chip)
 
        guard(mutex)(&chip->i2c_lock);
 
+       if (chip->client->irq > 0)
+               enable_irq(chip->client->irq);
        regcache_cache_only(chip->regmap, false);
        regcache_mark_dirty(chip->regmap);
        ret = pca953x_regcache_sync(chip);
@@ -1221,6 +1223,10 @@ static int pca953x_restore_context(struct pca953x_chip *chip)
 static void pca953x_save_context(struct pca953x_chip *chip)
 {
        guard(mutex)(&chip->i2c_lock);
+
+       /* Disable IRQ to prevent early triggering while regmap "cache only" is on */
+       if (chip->client->irq > 0)
+               disable_irq(chip->client->irq);
        regcache_cache_only(chip->regmap, true);
 }