linux-kernel - [PATCH 03/14 v1] usb: typec: tcpci: update ROLE

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Message-Id: <20200825042210.300632-4-badhri@google.com>
Date:   Mon, 24 Aug 2020 21:21:59 -0700
From:   Badhri Jagan Sridharan <badhri@...gle.com>
To:     Guenter Roeck <linux@...ck-us.net>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Badhri Jagan Sridharan <badhri@...gle.com>
Subject: [PATCH 03/14 v1] usb: typec: tcpci: update ROLE_CONTROL for DRP

ROLE_CONTROL register would not have the actual CC terminations
unless the port does not set ROLE_CONTROL.DRP. For DRP ports,
CC_STATUS.cc1/cc2 indicates the final terminations applied
when TCPC enters potential_connect_as_source/_sink.
For DRP ports, infer port role from CC_STATUS and set corresponding
CC terminations before setting the orientation.

Signed-off-by: Badhri Jagan Sridharan <badhri@...gle.com>
---
 drivers/usb/typec/tcpm/tcpci.c | 37 +++++++++++++++++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/typec/tcpm/tcpci.c b/drivers/usb/typec/tcpm/tcpci.c
index 90d348caa6a8..9e814d454d14 100644
--- a/drivers/usb/typec/tcpm/tcpci.c
+++ b/drivers/usb/typec/tcpm/tcpci.c
@@ -191,12 +191,47 @@ static int tcpci_set_polarity(struct tcpc_dev *tcpc,
 	struct tcpci *tcpci = tcpc_to_tcpci(tcpc);
 	unsigned int reg;
 	int ret;
+	enum typec_cc_status cc1, cc2;
 
-	/* Keep the disconnect cc line open */
+	/* Obtain Rp setting from role control */
 	ret = regmap_read(tcpci->regmap, TCPC_ROLE_CTRL, &reg);
 	if (ret < 0)
 		return ret;
 
+	ret = tcpci_get_cc(tcpc, &cc1, &cc2);
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * When port has drp toggling enabled, ROLE_CONTROL would only have the initial
+	 * terminations for the toggling and does not indicate the final cc
+	 * terminations when ConnectionResult is 0 i.e. drp toggling stops and
+	 * the connection is resolbed. Infer port role from TCPC_CC_STATUS based on the
+	 * terminations seen. The port role is then used to set the cc terminations.
+	 */
+	if (reg & TCPC_ROLE_CTRL_DRP) {
+		/* Disable DRP for the OPEN setting to take effect */
+		reg = reg & ~TCPC_ROLE_CTRL_DRP;
+
+		if (polarity == TYPEC_POLARITY_CC2) {
+			reg &= ~(TCPC_ROLE_CTRL_CC2_MASK << TCPC_ROLE_CTRL_CC2_SHIFT);
+			/* Local port is source */
+			if (cc2 == TYPEC_CC_RD)
+				/* Role control would have the Rp setting when DRP was enabled */
+				reg |= TCPC_ROLE_CTRL_CC_RP << TCPC_ROLE_CTRL_CC2_SHIFT;
+			else
+				reg |= TCPC_ROLE_CTRL_CC_RD << TCPC_ROLE_CTRL_CC2_SHIFT;
+		} else {
+			reg &= ~(TCPC_ROLE_CTRL_CC1_MASK << TCPC_ROLE_CTRL_CC1_SHIFT);
+			/* Local port is source */
+			if (cc1 == TYPEC_CC_RD)
+				/* Role control would have the Rp setting when DRP was enabled */
+				reg |= TCPC_ROLE_CTRL_CC_RP << TCPC_ROLE_CTRL_CC1_SHIFT;
+			else
+				reg |= TCPC_ROLE_CTRL_CC_RD << TCPC_ROLE_CTRL_CC1_SHIFT;
+		}
+	}
+
 	if (polarity == TYPEC_POLARITY_CC2)
 		reg |= TCPC_ROLE_CTRL_CC_OPEN << TCPC_ROLE_CTRL_CC1_SHIFT;
 	else
-- 
2.28.0.297.g1956fa8f8d-goog