counter: 104-quad-8: Fix incorrect return value in IRQ handler

quad8_irq_handler() should return irqreturn_t enum values, but it
directly returns negative errno codes from regmap operations on error.

Return IRQ_NONE if the interrupt status cannot be read. If clearing the
interrupt fails, return IRQ_HANDLED to prevent the kernel from disabling
the IRQ line due to a spurious interrupt storm. Also, log these regmap
failures with dev_WARN_ONCE.

Fixes: 98ffe02 ("counter: 104-quad-8: Migrate to the regmap API")
Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Haotian Zhang <vulab@iscas.ac.cn>
Link: https://lore.kernel.org/r/20251215020114.1913-1-vulab@iscas.ac.cn
Cc: stable@vger.kernel.org
Signed-off-by: William Breathitt Gray <wbg@kernel.org>

Author: ISCAS-Vulab

drivers/counter/104-quad-8.c

@@ -1192,6 +1192,7 @@ static irqreturn_t quad8_irq_handler(int irq, void *private)
 {
 	struct counter_device *counter = private;
 	struct quad8 *const priv = counter_priv(counter);
+	struct device *dev = counter->parent;
 	unsigned int status;
 	unsigned long irq_status;
 	unsigned long channel;
@@ -1200,8 +1201,11 @@ static irqreturn_t quad8_irq_handler(int irq, void *private)
 	int ret;
 
 	ret = regmap_read(priv->map, QUAD8_INTERRUPT_STATUS, &status);
-	if (ret)
-		return ret;
+	if (ret) {
+		dev_WARN_ONCE(dev, true,
+			"Attempt to read Interrupt Status Register failed: %d\n", ret);
+		return IRQ_NONE;
+	}
 	if (!status)
 		return IRQ_NONE;
 
@@ -1223,17 +1227,21 @@ static irqreturn_t quad8_irq_handler(int irq, void *private)
 				break;
 		default:
 			/* should never reach this path */
-			WARN_ONCE(true, "invalid interrupt trigger function %u configured for channel %lu\n",
-				  flg_pins, channel);
+			dev_WARN_ONCE(dev, true,
+				"invalid interrupt trigger function %u configured for channel %lu\n",
+				flg_pins, channel);
 			continue;
 		}
 
 		counter_push_event(counter, event, channel);
 	}
 
 	ret = regmap_write(priv->map, QUAD8_CHANNEL_OPERATION, CLEAR_PENDING_INTERRUPTS);
-	if (ret)
-		return ret;
+	if (ret) {
+		dev_WARN_ONCE(dev, true,
+			"Attempt to clear pending interrupts by writing to Channel Operation Register failed: %d\n", ret);
+		return IRQ_HANDLED;
+	}
 
 	return IRQ_HANDLED;
 }