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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Guenter Roeck <linux@roeck-us.net>,
        Heikki Krogerus <heikki.krogerus@linux.intel.com>,
        Li Jun <jun.li@nxp.com>, ChiYuan Huang <cy_huang@richtek.com>
Subject: [PATCH 4.19 141/191] usb: typec: tcpm: reset hard_reset_count for any disconnect
Date:   Tue,  3 Nov 2020 21:37:13 +0100
Message-Id: <20201103203246.070370592@linuxfoundation.org>
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From: Li Jun <jun.li@nxp.com>

commit 2d9c6442a9c81f4f8dee678d0b3c183173ab1e2d upstream.

Current tcpm_detach() only reset hard_reset_count if port->attached
is true, this may cause this counter clear is missed if the CC
disconnect event is generated after tcpm_port_reset() is done
by other events, e.g. VBUS off comes first before CC disconect for
a power sink, in that case the first tcpm_detach() will only clear
port->attached flag but leave hard_reset_count there because
tcpm_port_is_disconnected() is still false, then later tcpm_detach()
by CC disconnect will directly return due to port->attached is cleared,
finally this will result tcpm will not try hard reset or error recovery
for later attach.

ChiYuan reported this issue on his platform with below tcpm trace:
After power sink session setup after hard reset 2 times, detach
from the power source and then attach:
[ 4848.046358] VBUS off
[ 4848.046384] state change SNK_READY -> SNK_UNATTACHED
[ 4848.050908] Setting voltage/current limit 0 mV 0 mA
[ 4848.050936] polarity 0
[ 4848.052593] Requesting mux state 0, usb-role 0, orientation 0
[ 4848.053222] Start toggling
[ 4848.086500] state change SNK_UNATTACHED -> TOGGLING
[ 4848.089983] CC1: 0 -> 0, CC2: 3 -> 3 [state TOGGLING, polarity 0, connected]
[ 4848.089993] state change TOGGLING -> SNK_ATTACH_WAIT
[ 4848.090031] pending state change SNK_ATTACH_WAIT -> SNK_DEBOUNCED @200 ms
[ 4848.141162] CC1: 0 -> 0, CC2: 3 -> 0 [state SNK_ATTACH_WAIT, polarity 0, disconnected]
[ 4848.141170] state change SNK_ATTACH_WAIT -> SNK_ATTACH_WAIT
[ 4848.141184] pending state change SNK_ATTACH_WAIT -> SNK_UNATTACHED @20 ms
[ 4848.163156] state change SNK_ATTACH_WAIT -> SNK_UNATTACHED [delayed 20 ms]
[ 4848.163162] Start toggling
[ 4848.216918] CC1: 0 -> 0, CC2: 0 -> 3 [state TOGGLING, polarity 0, connected]
[ 4848.216954] state change TOGGLING -> SNK_ATTACH_WAIT
[ 4848.217080] pending state change SNK_ATTACH_WAIT -> SNK_DEBOUNCED @200 ms
[ 4848.231771] CC1: 0 -> 0, CC2: 3 -> 0 [state SNK_ATTACH_WAIT, polarity 0, disconnected]
[ 4848.231800] state change SNK_ATTACH_WAIT -> SNK_ATTACH_WAIT
[ 4848.231857] pending state change SNK_ATTACH_WAIT -> SNK_UNATTACHED @20 ms
[ 4848.256022] state change SNK_ATTACH_WAIT -> SNK_UNATTACHED [delayed20 ms]
[ 4848.256049] Start toggling
[ 4848.871148] VBUS on
[ 4848.885324] CC1: 0 -> 0, CC2: 0 -> 3 [state TOGGLING, polarity 0, connected]
[ 4848.885372] state change TOGGLING -> SNK_ATTACH_WAIT
[ 4848.885548] pending state change SNK_ATTACH_WAIT -> SNK_DEBOUNCED @200 ms
[ 4849.088240] state change SNK_ATTACH_WAIT -> SNK_DEBOUNCED [delayed200 ms]
[ 4849.088284] state change SNK_DEBOUNCED -> SNK_ATTACHED
[ 4849.088291] polarity 1
[ 4849.088769] Requesting mux state 1, usb-role 2, orientation 2
[ 4849.088895] state change SNK_ATTACHED -> SNK_STARTUP
[ 4849.088907] state change SNK_STARTUP -> SNK_DISCOVERY
[ 4849.088915] Setting voltage/current limit 5000 mV 0 mA
[ 4849.088927] vbus=0 charge:=1
[ 4849.090505] state change SNK_DISCOVERY -> SNK_WAIT_CAPABILITIES
[ 4849.090828] pending state change SNK_WAIT_CAPABILITIES -> SNK_READY @240 ms
[ 4849.335878] state change SNK_WAIT_CAPABILITIES -> SNK_READY [delayed240 ms]

this patch fix this issue by clear hard_reset_count at any cases
of cc disconnect, í.e. don't check port->attached flag.

Fixes: 4b4e02c83167 ("typec: tcpm: Move out of staging")
Cc: stable@vger.kernel.org
Reported-and-tested-by: ChiYuan Huang <cy_huang@richtek.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Li Jun <jun.li@nxp.com>
Link: https://lore.kernel.org/r/1602500592-3817-1-git-send-email-jun.li@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/usb/typec/tcpm.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/usb/typec/tcpm.c
+++ b/drivers/usb/typec/tcpm.c
@@ -2727,12 +2727,12 @@ static void tcpm_reset_port(struct tcpm_
 
 static void tcpm_detach(struct tcpm_port *port)
 {
-	if (!port->attached)
-		return;
-
 	if (tcpm_port_is_disconnected(port))
 		port->hard_reset_count = 0;
 
+	if (!port->attached)
+		return;
+
 	tcpm_reset_port(port);
 }