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

commit 5638b0dfb6921f69943c705383ff40fb64b987f2 upstream.

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@vger.kernel.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Xu Yang <xu.yang_2@nxp.com>
Link: https://lore.kernel.org/r/20220113092943.752372-1-xu.yang_2@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/typec/tcpm/tcpci.c b/drivers/usb/typec/tcpm/tcpci.c
index c15eec9cc460a01a96553c00c52dda166767b028..7d540afdb7cc31d76ff54f2f67df89728f92eedf 100644 (file)
--- 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 2be7a77d400ef9da9f0c22b8d4076379d190f1a8..b2edd45f13c681a5a6a0a4b49f9c389e537f7f4f 100644 (file)
--- 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