[PATCH] gpiolib: acpi: Only trigger ActiveBoth interrupts on boot

[Mario Limonciello <mario.limonciello@amd.com>]

Commit ca876c7483b6 ("gpiolib-acpi: make sure we trigger edge events at
least once on boot") introduced logic to trigger edge-based GPIO
interrupts during initialization to ensure proper initial state setup
when firmware doesn't initialize it.

However, according to the Microsoft GPIO documentation, triggering GPIO
interrupts during initialization should only happen for interrupts
marked as ActiveBoth (both IRQF_TRIGGER_RISING and IRQF_TRIGGER_FALLING)
and only when the associated GPIO line is already asserted (logic level
low).

The current implementation incorrectly triggers:
1. Any edge-triggered interrupt (RISING-only or FALLING-only)
2. RISING interrupts when value is high and FALLING when value is low

This causes problems at bootup for single-edge interrupts that
don't follow the ActiveBoth pattern.

Fix this by:
- Only triggering when BOTH rising and falling edges are configured
- Only triggering when the GPIO line is asserted (value == 0)

Reported-by: Francesco Lauritano <francesco.lauritano1@protonmail.com>
Closes: https://lore.kernel.org/all/6iFCwGH2vssb7NRUTWGpkubGMNbgIlBHSz40z8ZsezjxngXpoiiRiJaijviNvhiDAGIr43bfUmdxLmxYoHDjyft4DgwFc3Pnu5hzPguTa0s=@protonmail.com/
Tested-by: Marco Scardovi <mscardovi95@gmail.com>
Fixes: ca876c7483b69 ("gpiolib-acpi: make sure we trigger edge events at least once on boot")
Link: https://learn.microsoft.com/en-us/windows-hardware/drivers/bringup/general-purpose-i-o--gpio-
Suggested-by: Armin Wolf <W_Armin@gmx.de>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
 drivers/gpio/gpiolib-acpi-core.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/gpio/gpiolib-acpi-core.c b/drivers/gpio/gpiolib-acpi-core.c
index 09f860200a059..eb8a40cfb7a98 100644
--- a/drivers/gpio/gpiolib-acpi-core.c
+++ b/drivers/gpio/gpiolib-acpi-core.c
@@ -233,12 +233,23 @@ static void acpi_gpiochip_request_irq(struct acpi_gpio_chip *acpi_gpio,
 
 	event->irq_requested = true;
 
-	/* Make sure we trigger the initial state of edge-triggered IRQs */
+	/*
+	 * Make sure we trigger the initial state of ActiveBoth IRQs.
+	 *
+	 * According to the Microsoft GPIO documentation, triggering GPIO
+	 * interrupts marked as ActiveBoth during initialization is correct
+	 * as long as the associated GPIO line is already "asserted"
+	 * (logic level low). We should not trigger edge-based GPIO
+	 * interrupts not marked as ActiveBoth.
+	 *
+	 * See: https://learn.microsoft.com/en-us/windows-hardware/drivers/bringup/general-purpose-i-o--gpio-
+	 * Section: "GPIO controllers and ActiveBoth interrupts"
+	 */
 	if (acpi_gpio_need_run_edge_events_on_boot() &&
-	    (event->irqflags & (IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING))) {
+	    ((event->irqflags & (IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING)) ==
+	     (IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING))) {
 		value = gpiod_get_raw_value_cansleep(event->desc);
-		if (((event->irqflags & IRQF_TRIGGER_RISING) && value == 1) ||
-		    ((event->irqflags & IRQF_TRIGGER_FALLING) && value == 0))
+		if (value == 0)
 			event->handler(event->irq, event);
 	}
 }
-- 
2.43.0