usb: typec: tcpci: don't handle vSafe0V event if it's not enabled

USB TCPCI Spec, 4.4.3 Mask Registers:
"A masked register will still indicate in the ALERT register, but shall
not set the Alert# pin low."

Thus, the Extended Status will still indicate in ALERT register if vSafe0V
is detected by TCPC even though being masked. In current code, howerer,
this event will not be handled in detection time. Rather it will be
handled when next ALERT event coming(CC evnet, PD event, etc).

Tcpm might transition to a wrong state in this situation. Thus, the vSafe0V
event should not be handled when it's masked.

Fixes: 766c485 ("usb: typec: tcpci: Add support to report vSafe0V")
cc: <[email protected]>
Reviewed-by: Guenter Roeck <[email protected]>
Acked-by: Heikki Krogerus <[email protected]>
Signed-off-by: Xu Yang <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Xu Yang

drivers/usb/typec/tcpm/tcpci.c

@@ -696,7 +696,7 @@ irqreturn_t tcpci_irq(struct tcpci *tcpci)
 		tcpm_pd_receive(tcpci->port, &msg);
 	}
 
-	if (status & TCPC_ALERT_EXTENDED_STATUS) {
+	if (tcpci->data->vbus_vsafe0v && (status & TCPC_ALERT_EXTENDED_STATUS)) {
 		ret = regmap_read(tcpci->regmap, TCPC_EXTENDED_STATUS, &raw);
 		if (!ret && (raw & TCPC_EXTENDED_STATUS_VSAFE0V))
 			tcpm_vbus_change(tcpci->port);