diff mbox series

[v3] gpio: pca953x: fix IRQ storm on system wake up

Message ID 20250512095441.31645-1-francesco@dolcini.it
State New
Headers show
Series [v3] gpio: pca953x: fix IRQ storm on system wake up | expand

Commit Message

Francesco Dolcini May 12, 2025, 9:54 a.m. UTC 
From: Emanuele Ghidoli <emanuele.ghidoli@toradex.com>

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>
---
v2 -> v3
 - add r-b Andy, t-b Geert
 - fixed commit message

v1 -> v2
 - Instead of calling PM ops with disabled interrupts, just disable the
   irq while going in suspend and re-enable it after restoring the
   context in resume function.
---
 drivers/gpio/gpio-pca953x.c | 6 ++++++
 1 file changed, 6 insertions(+)

Comments

Bartosz Golaszewski May 13, 2025, 11:02 a.m. UTC | #1 
From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>


On Mon, 12 May 2025 11:54:41 +0200, Francesco Dolcini wrote:
> 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.
> 
> [...]

Applied, thanks!

[1/1] gpio: pca953x: fix IRQ storm on system wake up
      https://git.kernel.org/brgl/linux/c/3e38f946062b4845961ab86b726651b4457b2af8

Best regards,
diff mbox series

Patch

diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c
index ab2c0fd428fb..b852e4997629 100644
--- a/drivers/gpio/gpio-pca953x.c
+++ b/drivers/gpio/gpio-pca953x.c
@@ -1226,6 +1226,8 @@  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);
@@ -1238,6 +1240,10 @@  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);
 }