Date:   Wed, 24 Nov 2021 14:40:36 -0800
Message-Id: <20211124224036.734679-1-badhri@google.com>
Mime-Version: 1.0
Subject: [PATCH v1] usb: typec: tcpm: Wait in SNK_DEBOUNCED until disconnect
From:   Badhri Jagan Sridharan <badhri@google.com>
To:     Guenter Roeck <linux@roeck-us.net>,
        Heikki Krogerus <heikki.krogerus@linux.intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
        Kyle Tso <kyletso@google.com>, stable@vger.kernel.org,
        Badhri Jagan Sridharan <badhri@google.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Stub from the spec:
"4.5.2.2.4.2 Exiting from AttachWait.SNK State
A Sink shall transition to Unattached.SNK when the state of both
the CC1 and CC2 pins is SNK.Open for at least tPDDebounce.
A DRP shall transition to Unattached.SRC when the state of both
the CC1 and CC2 pins is SNK.Open for at least tPDDebounce."

This change makes TCPM to wait in SNK_DEBOUNCED state until
CC1 and CC2 pins is SNK.Open for at least tPDDebounce. Previously,
TCPM resets the port if vbus is not present in PD_T_PS_SOURCE_ON.
This causes TCPM to loop continuously when connected to a
faulty power source that does not present vbus. Waiting in
SNK_DEBOUNCED also ensures that TCPM is adherant to
"4.5.2.2.4.2 Exiting from AttachWait.SNK State" requirements.

[ 6169.280751] CC1: 0 -> 0, CC2: 0 -> 5 [state TOGGLING, polarity 0, connected]
[ 6169.280759] state change TOGGLING -> SNK_ATTACH_WAIT [rev2 NONE_AMS]
[ 6169.280771] pending state change SNK_ATTACH_WAIT -> SNK_DEBOUNCED @ 170 ms [rev2 NONE_AMS]
[ 6169.282427] CC1: 0 -> 0, CC2: 5 -> 5 [state SNK_ATTACH_WAIT, polarity 0, connected]
[ 6169.450825] state change SNK_ATTACH_WAIT -> SNK_DEBOUNCED [delayed 170 ms]
[ 6169.450834] pending state change SNK_DEBOUNCED -> PORT_RESET @ 480 ms [rev2 NONE_AMS]
[ 6169.930892] state change SNK_DEBOUNCED -> PORT_RESET [delayed 480 ms]
[ 6169.931296] disable vbus discharge ret:0
[ 6169.931301] Setting usb_comm capable false
[ 6169.932783] Setting voltage/current limit 0 mV 0 mA
[ 6169.932802] polarity 0
[ 6169.933706] Requesting mux state 0, usb-role 0, orientation 0
[ 6169.936689] cc:=0
[ 6169.936812] pending state change PORT_RESET -> PORT_RESET_WAIT_OFF @ 100 ms [rev2 NONE_AMS]
[ 6169.937157] CC1: 0 -> 0, CC2: 5 -> 0 [state PORT_RESET, polarity 0, disconnected]
[ 6170.036880] state change PORT_RESET -> PORT_RESET_WAIT_OFF [delayed 100 ms]
[ 6170.036890] state change PORT_RESET_WAIT_OFF -> SNK_UNATTACHED [rev2 NONE_AMS]
[ 6170.036896] Start toggling
[ 6170.041412] CC1: 0 -> 0, CC2: 0 -> 0 [state TOGGLING, polarity 0, disconnected]
[ 6170.042973] CC1: 0 -> 0, CC2: 0 -> 5 [state TOGGLING, polarity 0, connected]
[ 6170.042976] state change TOGGLING -> SNK_ATTACH_WAIT [rev2 NONE_AMS]
[ 6170.042981] pending state change SNK_ATTACH_WAIT -> SNK_DEBOUNCED @ 170 ms [rev2 NONE_AMS]
[ 6170.213014] state change SNK_ATTACH_WAIT -> SNK_DEBOUNCED [delayed 170 ms]
[ 6170.213019] pending state change SNK_DEBOUNCED -> PORT_RESET @ 480 ms [rev2 NONE_AMS]
[ 6170.693068] state change SNK_DEBOUNCED -> PORT_RESET [delayed 480 ms]
[ 6170.693304] disable vbus discharge ret:0
[ 6170.693308] Setting usb_comm capable false
[ 6170.695193] Setting voltage/current limit 0 mV 0 mA
[ 6170.695210] polarity 0
[ 6170.695990] Requesting mux state 0, usb-role 0, orientation 0
[ 6170.701896] cc:=0
[ 6170.702181] pending state change PORT_RESET -> PORT_RESET_WAIT_OFF @ 100 ms [rev2 NONE_AMS]
[ 6170.703343] CC1: 0 -> 0, CC2: 5 -> 0 [state PORT_RESET, polarity 0, disconnected]

Fixes: f0690a25a140b8 ("staging: typec: USB Type-C Port Manager (tcpm)")
Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
---
 drivers/usb/typec/tcpm/tcpm.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index 7f2f3ff1b391..6010b9901126 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -4110,11 +4110,7 @@ static void run_state_machine(struct tcpm_port *port)
 				       tcpm_try_src(port) ? SRC_TRY
 							  : SNK_ATTACHED,
 				       0);
-		else
-			/* Wait for VBUS, but not forever */
-			tcpm_set_state(port, PORT_RESET, PD_T_PS_SOURCE_ON);
 		break;
-
 	case SRC_TRY:
 		port->try_src_count++;
 		tcpm_set_cc(port, tcpm_rp_cc(port));
-- 
2.34.0.rc2.393.gf8c9666880-goog