linux-kernel - [PATCH] usb: typec: tcpm: Relax disconnect threshold during power negotiation

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Message-Id: <20210613151223.563736-1-kyletso@google.com>
Date:   Sun, 13 Jun 2021 23:12:23 +0800
From:   Kyle Tso <kyletso@...gle.com>
To:     linux@...ck-us.net, heikki.krogerus@...ux.intel.com,
        gregkh@...uxfoundation.org
Cc:     badhri@...gle.com, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, Kyle Tso <kyletso@...gle.com>
Subject: [PATCH] usb: typec: tcpm: Relax disconnect threshold during power negotiation

If the voltage is being decreased in power negotiation, the Source will
set the power supply to operate at the new voltage level before sending
PS_RDY. Relax the disconnect threshold for Sink after receiving Accept
Message to ensure the relaxed setting is enabled before the voltage
collapse. And the real threshold will be set after Sink receives PS_RDY
Message.

Fixes: f321a02caebd ("usb: typec: tcpm: Implement enabling Auto Discharge disconnect support")
Cc: Badhri Jagan Sridharan <badhri@...gle.com>
Signed-off-by: Kyle Tso <kyletso@...gle.com>
---
 drivers/usb/typec/tcpm/tcpm.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index 0db685d5d9c0..9f3f37da71b6 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -2646,6 +2646,8 @@ static void tcpm_pd_ctrl_request(struct tcpm_port *port,
 		switch (port->state) {
 		case SNK_NEGOTIATE_CAPABILITIES:
 			port->pps_data.active = false;
+			/* Voltage is going to be at new level. Relax the threshold here. */
+			tcpm_set_auto_vbus_discharge_threshold(port, TYPEC_PWR_MODE_USB, false, 0);
 			tcpm_set_state(port, SNK_TRANSITION_SINK, 0);
 			break;
 		case SNK_NEGOTIATE_PPS_CAPABILITIES:
@@ -2656,6 +2658,8 @@ static void tcpm_pd_ctrl_request(struct tcpm_port *port,
 			port->req_supply_voltage = port->pps_data.req_out_volt;
 			port->req_current_limit = port->pps_data.req_op_curr;
 			power_supply_changed(port->psy);
+			/* Voltage is going to be at new level. Relax the threshold here. */
+			tcpm_set_auto_vbus_discharge_threshold(port, TYPEC_PWR_MODE_USB, false, 0);
 			tcpm_set_state(port, SNK_TRANSITION_SINK, 0);
 			break;
 		case SOFT_RESET_SEND:
-- 
2.32.0.272.g935e593368-goog