[PATCH v3] usb: typec: tcpci: clear the fault status bit

[Fabio Estevam <festevam@gmail.com>]

From: Marco Felsch <m.felsch@pengutronix.de>

According the "USB Type-C Port Controller Interface Specification v2.0"
the TCPC sets the fault status register bit-7
(AllRegistersResetToDefault) once the registers have been reset to
their default values.

This triggers an alert(-irq) on PTN5110 devices albeit we do mask the
fault-irq, which may cause a kernel hang. Fix this generically by writing
a one to the corresponding bit-7.

Cc: stable@vger.kernel.org
Fixes: 74e656d6b055 ("staging: typec: Type-C Port Controller Interface driver (tcpci)")
Reported-by: Angus Ainslie (Purism) <angus@akkea.ca>
Closes: https://lore.kernel.org/all/20190508002749.14816-2-angus@akkea.ca/
Reported-by: Christian Bach <christian.bach@scs.ch>
Closes: https://lore.kernel.org/regressions/ZR0P278MB07737E5F1D48632897D51AC3EB329@ZR0P278MB0773.CHEP278.PROD.OUTLOOK.COM/t/
Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Signed-off-by: Fabio Estevam <festevam@denx.de>
---
Changes since v2:
- Submitted it as a standalone patch.
- Explain that it may cause a kernel hang.
- Fixed typos in the commit log. (Guenter)
- Check the tcpci_write16() return value. (Guenter)
- Write to TCPC_FAULT_STATUS unconditionally. (Guenter)
- Added Fixes, Reported-by and Closes tags.
- CCed stable

 drivers/usb/typec/tcpm/tcpci.c | 4 ++++
 include/linux/usb/tcpci.h      | 1 +
 2 files changed, 5 insertions(+)

diff --git a/drivers/usb/typec/tcpm/tcpci.c b/drivers/usb/typec/tcpm/tcpci.c
index fc708c289a73..0ee3e6e29bb1 100644
--- a/drivers/usb/typec/tcpm/tcpci.c
+++ b/drivers/usb/typec/tcpm/tcpci.c
@@ -602,6 +602,10 @@ static int tcpci_init(struct tcpc_dev *tcpc)
 	if (time_after(jiffies, timeout))
 		return -ETIMEDOUT;
 
+	ret = tcpci_write16(tcpci, TCPC_FAULT_STATUS, TCPC_FAULT_STATUS_ALL_REG_RST_TO_DEFAULT);
+	if (ret < 0)
+		return ret;
+
 	/* Handle vendor init */
 	if (tcpci->data->init) {
 		ret = tcpci->data->init(tcpci, tcpci->data);
diff --git a/include/linux/usb/tcpci.h b/include/linux/usb/tcpci.h
index 85e95a3251d3..83376473ac76 100644
--- a/include/linux/usb/tcpci.h
+++ b/include/linux/usb/tcpci.h
@@ -103,6 +103,7 @@
 #define TCPC_POWER_STATUS_SINKING_VBUS	BIT(0)
 
 #define TCPC_FAULT_STATUS		0x1f
+#define TCPC_FAULT_STATUS_ALL_REG_RST_TO_DEFAULT BIT(7)
 
 #define TCPC_ALERT_EXTENDED		0x21
 
-- 
2.34.1