patch "usb: typec: tcpci: don't touch CC line if it's Vconn source" added to usb-linus

[<gregkh@xxxxxxxxxxxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    usb: typec: tcpci: don't touch CC line if it's Vconn source

to my usb git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


>From 5638b0dfb6921f69943c705383ff40fb64b987f2 Mon Sep 17 00:00:00 2001
From: Xu Yang <xu.yang_2@xxxxxxx>
Date: Thu, 13 Jan 2022 17:29:43 +0800
Subject: usb: typec: tcpci: don't touch CC line if it's Vconn source

With the AMS and Collision Avoidance, tcpm often needs to change the CC's
termination. When one CC line is sourcing Vconn, if we still change its
termination, the voltage of the another CC line is likely to be fluctuant
and unstable.

Therefore, we should verify whether a CC line is sourcing Vconn before
changing its termination and only change the termination that is not
a Vconn line. This can be done by reading the Vconn Present bit of
POWER_ STATUS register. To determine the polarity, we can read the
Plug Orientation bit of TCPC_CONTROL register. Since Vconn can only be
sourced if Plug Orientation is set.

Fixes: 0908c5aca31e ("usb: typec: tcpm: AMS and Collision Avoidance")
cc: <stable@xxxxxxxxxxxxxxx>
Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Acked-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
Signed-off-by: Xu Yang <xu.yang_2@xxxxxxx>
Link: https://lore.kernel.org/r/20220113092943.752372-1-xu.yang_2@xxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/usb/typec/tcpm/tcpci.c | 26 ++++++++++++++++++++++++++
 drivers/usb/typec/tcpm/tcpci.h |  1 +
 2 files changed, 27 insertions(+)

diff --git a/drivers/usb/typec/tcpm/tcpci.c b/drivers/usb/typec/tcpm/tcpci.c
index 35a1307349a2..e07d26a3cd8e 100644
--- a/drivers/usb/typec/tcpm/tcpci.c
+++ b/drivers/usb/typec/tcpm/tcpci.c
@@ -75,9 +75,25 @@ static int tcpci_write16(struct tcpci *tcpci, unsigned int reg, u16 val)
 static int tcpci_set_cc(struct tcpc_dev *tcpc, enum typec_cc_status cc)
 {
 	struct tcpci *tcpci = tcpc_to_tcpci(tcpc);
+	bool vconn_pres;
+	enum typec_cc_polarity polarity = TYPEC_POLARITY_CC1;
 	unsigned int reg;
 	int ret;
 
+	ret = regmap_read(tcpci->regmap, TCPC_POWER_STATUS, &reg);
+	if (ret < 0)
+		return ret;
+
+	vconn_pres = !!(reg & TCPC_POWER_STATUS_VCONN_PRES);
+	if (vconn_pres) {
+		ret = regmap_read(tcpci->regmap, TCPC_TCPC_CTRL, &reg);
+		if (ret < 0)
+			return ret;
+
+		if (reg & TCPC_TCPC_CTRL_ORIENTATION)
+			polarity = TYPEC_POLARITY_CC2;
+	}
+
 	switch (cc) {
 	case TYPEC_CC_RA:
 		reg = (TCPC_ROLE_CTRL_CC_RA << TCPC_ROLE_CTRL_CC1_SHIFT) |
@@ -112,6 +128,16 @@ static int tcpci_set_cc(struct tcpc_dev *tcpc, enum typec_cc_status cc)
 		break;
 	}
 
+	if (vconn_pres) {
+		if (polarity == TYPEC_POLARITY_CC2) {
+			reg &= ~(TCPC_ROLE_CTRL_CC1_MASK << TCPC_ROLE_CTRL_CC1_SHIFT);
+			reg |= (TCPC_ROLE_CTRL_CC_OPEN << TCPC_ROLE_CTRL_CC1_SHIFT);
+		} else {
+			reg &= ~(TCPC_ROLE_CTRL_CC2_MASK << TCPC_ROLE_CTRL_CC2_SHIFT);
+			reg |= (TCPC_ROLE_CTRL_CC_OPEN << TCPC_ROLE_CTRL_CC2_SHIFT);
+		}
+	}
+
 	ret = regmap_write(tcpci->regmap, TCPC_ROLE_CTRL, reg);
 	if (ret < 0)
 		return ret;
diff --git a/drivers/usb/typec/tcpm/tcpci.h b/drivers/usb/typec/tcpm/tcpci.h
index 2be7a77d400e..b2edd45f13c6 100644
--- a/drivers/usb/typec/tcpm/tcpci.h
+++ b/drivers/usb/typec/tcpm/tcpci.h
@@ -98,6 +98,7 @@
 #define TCPC_POWER_STATUS_SOURCING_VBUS	BIT(4)
 #define TCPC_POWER_STATUS_VBUS_DET	BIT(3)
 #define TCPC_POWER_STATUS_VBUS_PRES	BIT(2)
+#define TCPC_POWER_STATUS_VCONN_PRES	BIT(1)
 #define TCPC_POWER_STATUS_SINKING_VBUS	BIT(0)
 
 #define TCPC_FAULT_STATUS		0x1f
-- 
2.35.0