usb: typec: tcpm: enforce ready state when queueing alt mode vdm

Before sending Enter Mode for an Alt Mode, there is a gap between Discover
Modes and the Alt Mode driver queueing the Enter Mode VDM for the port
partner to send a message to the port.

If this message results in unregistering Alt Modes such as in a DR_SWAP,
then the following deadlock can occur with respect to the DisplayPort Alt
Mode driver:
1. The DR_SWAP state holds port->lock. Unregistering the Alt Mode driver
results in a cancel_work_sync() that waits for the current dp_altmode_work
to finish.
2. dp_altmode_work makes a call to tcpm_altmode_enter. The deadlock occurs
because tcpm_queue_vdm_unlock attempts to hold port->lock.

Before attempting to grab the lock, ensure that the port is in a state
vdm_run_state_machine can run in. Alt Mode unregistration will not occur
in these states.

Fixes: 03eafcf ("usb: typec: tcpm: Add tcpm_queue_vdm_unlocked() helper")
Cc: [email protected]
Signed-off-by: RD Babiera <[email protected]>
Reviewed-by: Heikki Krogerus <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: RD Babiera

drivers/usb/typec/tcpm/tcpm.c

@@ -1564,6 +1564,10 @@ 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, enum tcpm_transmit_type tx_sop_type)
 {
+	if (port->state != SRC_READY && port->state != SNK_READY &&
+	    port->state != SRC_VDM_IDENTITY_REQUEST)
+		return;
+
 	mutex_lock(&port->lock);
 	tcpm_queue_vdm(port, header, data, cnt, tx_sop_type);
 	mutex_unlock(&port->lock);