[PATCH v2 2/2] usb: typec: tcpci: write ALERT_MASK after devm_request_threaded_irq()

[Xu Yang <xu.yang_2@nxp.com>]

With edge irq support, the ALERT event may be missed currently. The reason
is that ALERT_MASK register is written before devm_request_threaded_irq().
If ALERT event happens in this time gap, it will be missed and ALERT line
will not recover to high level. However, we can't meet this issue with
level irq. To avoid the issue, this will add a flag set_alert_mask. So
ALERT_MASK can be written after devm_request_threaded_irq() is called. The
behavior of tcpm_init() keeps unchanged.

Fixes: 77e85107a771 ("usb: typec: tcpci: support edge irq")
Cc: stable@vger.kernel.org
Signed-off-by: Xu Yang <xu.yang_2@nxp.com>

---
Changes in v2:
 - new patch
---
 drivers/usb/typec/tcpm/tcpci.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/typec/tcpm/tcpci.c b/drivers/usb/typec/tcpm/tcpci.c
index db42f4bf3632..836f6d54d267 100644
--- a/drivers/usb/typec/tcpm/tcpci.c
+++ b/drivers/usb/typec/tcpm/tcpci.c
@@ -37,6 +37,7 @@ struct tcpci {
 	unsigned int alert_mask;
 
 	bool controls_vbus;
+	bool set_alert_mask;
 
 	struct tcpc_dev tcpc;
 	struct tcpci_data *data;
@@ -700,7 +701,10 @@ static int tcpci_init(struct tcpc_dev *tcpc)
 
 	tcpci->alert_mask = reg;
 
-	return tcpci_write16(tcpci, TCPC_ALERT_MASK, reg);
+	if (tcpci->set_alert_mask)
+		ret = tcpci_write16(tcpci, TCPC_ALERT_MASK, reg);
+
+	return ret;
 }
 
 irqreturn_t tcpci_irq(struct tcpci *tcpci)
@@ -931,12 +935,20 @@ static int tcpci_probe(struct i2c_client *client)
 					_tcpci_irq,
 					IRQF_SHARED | IRQF_ONESHOT,
 					dev_name(&client->dev), chip);
-	if (err < 0) {
-		tcpci_unregister_port(chip->tcpci);
-		return err;
-	}
+	if (err < 0)
+		goto unregister_port;
 
+	/* Enable the interrupt on chip at last */
+	err = tcpci_write16(chip->tcpci, TCPC_ALERT_MASK, chip->tcpci->alert_mask);
+	if (err < 0)
+		goto unregister_port;
+
+	chip->tcpci->set_alert_mask = true;
 	return 0;
+
+unregister_port:
+	tcpci_unregister_port(chip->tcpci);
+	return err;
 }
 
 static void tcpci_remove(struct i2c_client *client)
-- 
2.34.1