usb: typec: tcpm: Address incorrect values of tcpm psy for fixed supply

tcpm_pd_build_request overwrites current_limit and supply_voltage
even before port partner accepts the requests. This leaves stale
values in current_limit and supply_voltage that get exported by
"tcpm-source-psy-". Solving this problem by caching the request
values of current limit/supply voltage in req_current_limit
and req_supply_voltage. current_limit/supply_voltage gets updated
once the port partner accepts the request.

Fixes: f2a8aa05 ("typec: tcpm: Represent source supply through power_supply")
Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
Cc: stable <stable@vger.kernel.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20210407200723.1914388-1-badhri@google.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/typec/tcpm/tcpm.c

@@ -389,7 +389,10 @@ struct tcpm_port {
 	unsigned int operating_snk_mw;
 	bool update_sink_caps;
 
-	/* Requested current / voltage */
+	/* Requested current / voltage to the port partner */
+	u32 req_current_limit;
+	u32 req_supply_voltage;
+	/* Actual current / voltage limit of the local port */
 	u32 current_limit;
 	u32 supply_voltage;
 
@@ -2435,8 +2438,8 @@ static void tcpm_pd_ctrl_request(struct tcpm_port *port,
 		case SNK_TRANSITION_SINK:
 			if (port->vbus_present) {
 				tcpm_set_current_limit(port,
-						       port->current_limit,
-						       port->supply_voltage);
+						       port->req_current_limit,
+						       port->req_supply_voltage);
 				port->explicit_contract = true;
 				tcpm_set_auto_vbus_discharge_threshold(port,
 								       TYPEC_PWR_MODE_PD,
@@ -2545,8 +2548,8 @@ static void tcpm_pd_ctrl_request(struct tcpm_port *port,
 			break;
 		case SNK_NEGOTIATE_PPS_CAPABILITIES:
 			port->pps_data.active = true;
-			port->supply_voltage = port->pps_data.out_volt;
-			port->current_limit = port->pps_data.op_curr;
+			port->req_supply_voltage = port->pps_data.out_volt;
+			port->req_current_limit = port->pps_data.op_curr;
 			tcpm_set_state(port, SNK_TRANSITION_SINK, 0);
 			break;
 		case SOFT_RESET_SEND:
@@ -3195,8 +3198,8 @@ static int tcpm_pd_build_request(struct tcpm_port *port, u32 *rdo)
 			 flags & RDO_CAP_MISMATCH ? " [mismatch]" : "");
 	}
 
-	port->current_limit = ma;
-	port->supply_voltage = mv;
+	port->req_current_limit = ma;
+	port->req_supply_voltage = mv;
 
 	return 0;
 }