usb: typec: tcpm: add pd handler lock

Quickly plug and unplug the Type-C device with DP function test, there
is a low probability of unplugging the Type-C dongle, DP work cannot
acquire the mutex(port->lock), and it will always be stuck in the
tcpm_unregister_altmodes() function during the rest port process, causing
the Type-C device to be inserted again to fail to be detected or the reboot
system to be stuck. The exception process is as follows:
(1) Thread#1: unplug the Type-C device to trigger cc status changes interrupt, in the
    tcpm_pd_event_handler() function, first acquire the mutex(port->lock),
    then start state_machine work, and finally release the mutex(port->lock);
tcpm_cc_change()
  -->tcpm_pd_event_handler()
    -->mutex_lock(&port->lock)  /* step 1 */
    -->_tcpm_cc_change(port, cc1, cc2) /* step 2 */
      -->tcpm_set_state(port, SRC_UNATTACHED, 0)
        -->kthread_queue_work(port->wq, &port->state_machine) /* step 3 */
    --> mutex_unlock(&port->lock)  /* step 4 */

(2) Thread#2: before the execution of "step 2" is completed, DP work calls
    the callback function registered by the tcpm framework to initiate a VDM
    Message, such as Enter Mode Message, in the tcpm_queue_vdm_unlocked()
    acquires the mutex(port->lock) fails and goes to sleep;
dp_altmode_work()
  --> typec_altmode_enter(dp->alt)
    --> tcpm_altmode_enter()
      --> tcpm_queue_vdm_unlocked()
        --> mutex_lock(&port->lock) /* dp work enter sleep */

(3) After step 4, tcpm_queue_vdm_unlocked() did not acquire for the mutex
    (port->lock), but was preempted by the state_machine work to enter the reset
    port process. In the reset port process, call the tcpm_unregister_altmodes()
    function to release altmode and cancel dp work. Because tcpm_queue_vdm_unlocked()
    did not acquire the mutex(port->lock), causing it to be stuck in cancel dp work.
tcpm_state_machine_work()
  -->mutex_lock(&port->lock)
  -->tcpm_reset_port(port)
    -->tcpm_unregister_altmodes(port)
      ......
      --> dp_altmode_remove()
        --> cancel_work_sync(&dp->work) /* always stuck in cancel dp work */
  ......

Therefore, after adding a new mutex to wait for the tcpm_pd_event_handler() function
to complete the processing, if the port is in the disconnect state, there is no need
to acquire the mutex(port->lock) in the tcpm_queue_vdm_unlocked() function.

Change-Id: I364a035568ddc35ef7242b42f6d6d0ee3f5586fd
Signed-off-by: Wang Jie <dave.wang@rock-chips.com>

drivers/usb/typec/tcpm/tcpm.c

@@ -360,6 +360,7 @@ struct tcpm_port {
 	unsigned long delay_ms;
 
 	spinlock_t pd_event_lock;
+	struct mutex pd_handler_lock;
 	u32 pd_events;
 
 	struct kthread_work event_work;
@@ -1463,9 +1464,16 @@ static void tcpm_queue_vdm(struct tcpm_port *port, const u32 header,
 static void tcpm_queue_vdm_unlocked(struct tcpm_port *port, const u32 header,
 				    const u32 *data, int cnt)
 {
+	mutex_lock(&port->pd_handler_lock);
+	if (tcpm_port_is_disconnected(port))
+		goto unlock;
+
 	mutex_lock(&port->lock);
 	tcpm_queue_vdm(port, header, data, cnt);
 	mutex_unlock(&port->lock);
+
+unlock:
+	mutex_unlock(&port->pd_handler_lock);
 }
 
 static void svdm_consume_identity(struct tcpm_port *port, const u32 *p, int cnt)
@@ -5388,6 +5396,7 @@ static void tcpm_pd_event_handler(struct kthread_work *work)
 					      event_work);
 	u32 events;
 
+	mutex_lock(&port->pd_handler_lock);
 	mutex_lock(&port->lock);
 
 	spin_lock(&port->pd_event_lock);
@@ -5450,6 +5459,7 @@ static void tcpm_pd_event_handler(struct kthread_work *work)
 	}
 	spin_unlock(&port->pd_event_lock);
 	mutex_unlock(&port->lock);
+	mutex_unlock(&port->pd_handler_lock);
 }
 
 void tcpm_cc_change(struct tcpm_port *port)
@@ -6457,6 +6467,7 @@ struct tcpm_port *tcpm_register_port(struct device *dev, struct tcpc_dev *tcpc)
 
 	mutex_init(&port->lock);
 	mutex_init(&port->swap_lock);
+	mutex_init(&port->pd_handler_lock);
 
 	port->wq = kthread_create_worker(0, dev_name(dev));
 	if (IS_ERR(port->wq))