linux-kernel - [PATCH v1] usb: typec: tcpm: Update vbus

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Message-Id: <20201211071911.2205197-1-badhri@google.com>
Date:   Thu, 10 Dec 2020 23:19:11 -0800
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 v1] usb: typec: tcpm: Update vbus_vsafe0v on init

During init, vbus_vsafe0v does not get updated till the first
connect as a sink. This causes TCPM to be stuck in SRC_ATTACH_WAIT
state while booting with a sink (For instance: a headset) connected.

[    1.429168] Start toggling
[    1.439907] CC1: 0 -> 0, CC2: 0 -> 0 [state TOGGLING, polarity 0, disconnected]
[    1.445242] CC1: 0 -> 0, CC2: 0 -> 0 [state TOGGLING, polarity 0, disconnected]
[   53.358528] CC1: 0 -> 0, CC2: 0 -> 2 [state TOGGLING, polarity 0, connected]
[   53.358564] state change TOGGLING -> SRC_ATTACH_WAIT [rev1 NONE_AMS]

Fix this by updating vbus_vsafe0v based on vbus_present status
on boot.

Signed-off-by: Badhri Jagan Sridharan <badhri@...gle.com>
---
 drivers/usb/typec/tcpm/tcpm.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index cedc6cf82d61..58a6302c549f 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -4794,6 +4794,24 @@ static void tcpm_init(struct tcpm_port *port)
 	if (port->vbus_present)
 		port->vbus_never_low = true;
 
+	/*
+	 * 1. When vbus_present is true, voltage on VBUS is already at VSAFE5V.
+	 * So implicitly vbus_vsafe0v = false.
+	 *
+	 * 2. When vbus_present is false and TCPC does NOT support querying
+	 * vsafe0v status, then, it's best to assume vbus is at VSAFE0V i.e.
+	 * vbus_vsafe0v is true.
+	 *
+	 * 3. When vbus_present is false and TCPC does support querying vsafe0v,
+	 * then, query tcpc for vsafe0v status.
+	 */
+	if (port->vbus_present)
+		port->vbus_vsafe0v = false;
+	else if (!port->tcpc->is_vbus_vsafe0v)
+		port->vbus_vsafe0v = true;
+	else
+		port->vbus_vsafe0v = port->tcpc->is_vbus_vsafe0v(port->tcpc);
+
 	tcpm_set_state(port, tcpm_default_state(port), 0);
 
 	if (port->tcpc->get_cc(port->tcpc, &cc1, &cc2) == 0)
-- 
2.29.2.576.ga3fc446d84-goog