6.6-stable review patch. If anyone has any objections, please let me know.
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From: Emanuele Ghidoli emanuele.ghidoli@toradex.com
[ 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 --- drivers/gpio/gpio-pca953x.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c index a39c8ebd410e4..faadbe66b23e7 100644 --- 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); }