usb: typec: tcpci_maxim: Fix vbus stuck on upon diconnecting sink

Occasionally, POWER_STATUS.sourcing_vbus takes a while to clear after
writing to  MAX_BUCK_BOOST_OP register. This causes vbus to turn back
on while disconnecting the sink. Overcome this issue by writing into
MAX_BUCK_BOOST_OP during frs while sourcing vbu, instead of always
into the register whenever POWER_STATUS.sourcing_vbus is set.

Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20201029063138.1429760-7-badhri@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/typec/tcpm/tcpci_maxim.c

@@ -238,23 +238,22 @@ static void process_power_status(struct max_tcpci_chip *chip)
 	if (ret < 0)
 		return;
 
-	if (pwr_status == 0xff) {
+	if (pwr_status == 0xff)
 		max_tcpci_init_regs(chip);
-	} else if (pwr_status & TCPC_POWER_STATUS_SOURCING_VBUS) {
+	else if (pwr_status & TCPC_POWER_STATUS_SOURCING_VBUS)
 		tcpm_sourcing_vbus(chip->port);
-		/*
-		 * Alawys re-enable boost here.
-		 * In normal case, when say an headset is attached, TCPM would
-		 * have instructed to TCPC to enable boost, so the call is a
-		 * no-op.
-		 * But for Fast Role Swap case, Boost turns on autonomously without
-		 * AP intervention, but, needs AP to enable source mode explicitly
-		 * for AP to regain control.
-		 */
-		max_tcpci_set_vbus(chip->tcpci, &chip->data, true, false);
-	} else {
+	else
 		tcpm_vbus_change(chip->port);
-	}
+}
+
+static void max_tcpci_frs_sourcing_vbus(struct tcpci *tcpci, struct tcpci_data *tdata)
+{
+	/*
+	 * For Fast Role Swap case, Boost turns on autonomously without
+	 * AP intervention, but, needs AP to enable source mode explicitly
+	 * for AP to regain control.
+	 */
+	max_tcpci_set_vbus(tcpci, tdata, true, false);
 }
 
 static void process_tx(struct max_tcpci_chip *chip, u16 status)
@@ -441,6 +440,7 @@ static int max_tcpci_probe(struct i2c_client *client, const struct i2c_device_id
 	chip->data.start_drp_toggling = max_tcpci_start_toggling;
 	chip->data.TX_BUF_BYTE_x_hidden = true;
 	chip->data.init = tcpci_init;
+	chip->data.frs_sourcing_vbus = max_tcpci_frs_sourcing_vbus;
 
 	max_tcpci_init_regs(chip);
 	chip->tcpci = tcpci_register_port(chip->dev, &chip->data);