drivers/i2c: it81xx2: Avoid entering power policy during PIO transfers

Avoid entering low-power state during I2C host transfers in PIO mode.
Entering a low-power state during an active PIO transfer may prevent
the peripheral from generating the clock signal correctly,
resulting in transmission errors.

Signed-off-by: Tim Lin <[email protected]>

Author: GTLin08

drivers/i2c/i2c_ite_it8xxx2.c

@@ -944,6 +944,8 @@ static int i2c_it8xxx2_transfer(const struct device *dev, struct i2c_msg *msgs,
 
 	/* Lock mutex of i2c controller */
 	k_mutex_lock(&data->mutex, K_FOREVER);
+	/* Block to enter power policy. */
+	pm_policy_state_lock_get(PM_STATE_STANDBY, PM_ALL_SUBSTATES);
 	/*
 	 * If the transaction of write to read is divided into two
 	 * transfers, the repeat start transfer uses this flag to
@@ -961,9 +963,8 @@ static int i2c_it8xxx2_transfer(const struct device *dev, struct i2c_msg *msgs,
 			 * (No external pull-up), drop the transaction.
 			 */
 			if (i2c_bus_not_available(dev)) {
-				/* Unlock mutex of i2c controller */
-				k_mutex_unlock(&data->mutex);
-				return -EIO;
+				ret = -EIO;
+				goto done;
 			}
 		}
 
@@ -975,11 +976,6 @@ static int i2c_it8xxx2_transfer(const struct device *dev, struct i2c_msg *msgs,
 	/* Store msgs to data struct. */
 	data->msgs_list = msgs;
 	bool fifo_mode_enable = fifo_mode_allowed(dev, msgs);
-
-	if (fifo_mode_enable) {
-		/* Block to enter power policy. */
-		pm_policy_state_lock_get(PM_STATE_STANDBY, PM_ALL_SUBSTATES);
-	}
 #endif
 	for (int i = 0; i < num_msgs; i++) {
 
@@ -1056,8 +1052,6 @@ static int i2c_it8xxx2_transfer(const struct device *dev, struct i2c_msg *msgs,
 		if (data->num_msgs == 2) {
 			i2c_fifo_en_w2r(dev, 0);
 		}
-		/* Permit to enter power policy. */
-		pm_policy_state_lock_put(PM_STATE_STANDBY, PM_ALL_SUBSTATES);
 	}
 #endif
 	/* reset i2c channel status */
@@ -1066,6 +1060,10 @@ static int i2c_it8xxx2_transfer(const struct device *dev, struct i2c_msg *msgs,
 	}
 	/* Save return value. */
 	ret = i2c_parsing_return_value(dev);
+
+done:
+	/* Permit to enter power policy. */
+	pm_policy_state_lock_put(PM_STATE_STANDBY, PM_ALL_SUBSTATES);
 	/* Unlock mutex of i2c controller */
 	k_mutex_unlock(&data->mutex);