drm/bridge: it6505: Guard bridge power in IRQ handler

Add a pair of pm_runtime_get_if_in_use and pm_runtime_put_sync in the
interrupt handler to make sure the bridge won't be powered off during
the interrupt handlings. Also remove the irq_lock mutex because it's not
guarding anything now.

Fixes: ab28896f ("drm/bridge: it6505: Improve synchronization between extcon subsystem")
Signed-off-by: Pin-yen Lin <treapking@chromium.org>
Reviewed-by: Robert Foss <robert.foss@linaro.org>
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20221109095227.3320919-1-treapking@chromium.org

drivers/gpu/drm/bridge/ite-it6505.c

@@ -412,7 +412,6 @@ struct it6505 {
 	 * Mutex protects extcon and interrupt functions from interfering
 	 * each other.
 	 */
-	struct mutex irq_lock;
 	struct mutex extcon_lock;
 	struct mutex mode_lock; /* used to bridge_detect */
 	struct mutex aux_lock; /* used to aux data transfers */
@@ -2494,10 +2493,8 @@ static irqreturn_t it6505_int_threaded_handler(int unused, void *data)
 	};
 	int int_status[3], i;
 
-	mutex_lock(&it6505->irq_lock);
-
-	if (it6505->enable_drv_hold || !it6505->powered)
-		goto unlock;
+	if (it6505->enable_drv_hold || pm_runtime_get_if_in_use(dev) <= 0)
+		return IRQ_HANDLED;
 
 	int_status[0] = it6505_read(it6505, INT_STATUS_01);
 	int_status[1] = it6505_read(it6505, INT_STATUS_02);
@@ -2515,16 +2512,14 @@ static irqreturn_t it6505_int_threaded_handler(int unused, void *data)
 	if (it6505_test_bit(irq_vec[0].bit, (unsigned int *)int_status))
 		irq_vec[0].handler(it6505);
 
-	if (!it6505->hpd_state)
-		goto unlock;
-
-	for (i = 1; i < ARRAY_SIZE(irq_vec); i++) {
-		if (it6505_test_bit(irq_vec[i].bit, (unsigned int *)int_status))
-			irq_vec[i].handler(it6505);
+	if (it6505->hpd_state) {
+		for (i = 1; i < ARRAY_SIZE(irq_vec); i++) {
+			if (it6505_test_bit(irq_vec[i].bit, (unsigned int *)int_status))
+				irq_vec[i].handler(it6505);
+		}
 	}
 
-unlock:
-	mutex_unlock(&it6505->irq_lock);
+	pm_runtime_put_sync(dev);
 
 	return IRQ_HANDLED;
 }
@@ -3276,7 +3271,6 @@ static int it6505_i2c_probe(struct i2c_client *client)
 	if (!it6505)
 		return -ENOMEM;
 
-	mutex_init(&it6505->irq_lock);
 	mutex_init(&it6505->extcon_lock);
 	mutex_init(&it6505->mode_lock);
 	mutex_init(&it6505->aux_lock);