pinctrl: mcp23s08: Check only GPIOs which have interrupts enabled

GPINTEN register contains information about GPIOs with enabled
interrupts no need to check other GPIOs for changes.
Signed-off-by: Arturas Moskvinas <arturas.moskvinas@gmail.com>
Link: https://lore.kernel.org/r/20240201141406.32484-2-arturas.moskvinas@gmail.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/pinctrl-mcp23s08.c

@@ -375,7 +375,8 @@ mcp23s08_direction_output(struct gpio_chip *chip, unsigned offset, int value)
 static irqreturn_t mcp23s08_irq(int irq, void *data)
 {
 	struct mcp23s08 *mcp = data;
-	int intcap, intcon, intf, i, gpio, gpio_orig, intcap_mask, defval;
+	int intcap, intcon, intf, i, gpio, gpio_orig, intcap_mask, defval, gpinten;
+	unsigned long int enabled_interrupts;
 	unsigned int child_irq;
 	bool intf_set, intcap_changed, gpio_bit_changed,
 		defval_changed, gpio_set;
@@ -395,6 +396,9 @@ static irqreturn_t mcp23s08_irq(int irq, void *data)
 	if (mcp_read(mcp, MCP_INTCON, &intcon))
 		goto unlock;
 
+	if (mcp_read(mcp, MCP_GPINTEN, &gpinten))
+		goto unlock;
+
 	if (mcp_read(mcp, MCP_DEFVAL, &defval))
 		goto unlock;
 
@@ -410,9 +414,12 @@ static irqreturn_t mcp23s08_irq(int irq, void *data)
 		"intcap 0x%04X intf 0x%04X gpio_orig 0x%04X gpio 0x%04X\n",
 		intcap, intf, gpio_orig, gpio);
 
-	for (i = 0; i < mcp->chip.ngpio; i++) {
-		/* We must check all of the inputs on the chip,
-		 * otherwise we may not notice a change on >=2 pins.
+	enabled_interrupts = gpinten;
+	for_each_set_bit(i, &enabled_interrupts, mcp->chip.ngpio) {
+		/*
+		 * We must check all of the inputs with enabled interrupts
+		 * on the chip, otherwise we may not notice a change
+		 * on more than one pin.
 		 *
 		 * On at least the mcp23s17, INTCAP is only updated
 		 * one byte at a time(INTCAPA and INTCAPB are