usb: pd: Fix sink hard reset looping bug

commit f2449fb61a25 ("usb: pd: Clear PD_IN_HARD_RESET in
PE_SNK_TRANSITION_TO_DEFAULT") introduced a subtle bug by
moving the clearing of the pd->hard_reset flag in sink mode
to the PE_SNK_TRANSITION_TO_DEFAULT state. This caused a
regression in which the state machine acts as if it had
received a hard reset signal and infinitely loops back there.
The cycle could only be broken if a physical disconnect happens.
Fix this by renaming the flag to hard_reset_recvd and only using
it when receiving, and not sending a hard reset.

Change-Id: I04008d0bfc9a874e08b45f78a937004e9f37527d
Signed-off-by: Jack Pham <jackp@codeaurora.org>

1 files changed, 12 insertions, 18 deletions

diff --git a/drivers/usb/pd/policy_engine.c b/drivers/usb/pd/policy_engine.c
index a72c874f19a5..2eef9052bd00 100644
--- a/drivers/usb/pd/policy_engine.c
+++ b/drivers/usb/pd/policy_engine.c
@@ -274,7 +274,7 @@ struct usbpd {
 	struct extcon_dev	*extcon;
 
 	enum usbpd_state	current_state;
-	bool			hard_reset;
+	bool			hard_reset_recvd;
 	u8			rx_msg_type;
 	u8			rx_msg_len;
 	u32			rx_payload[7];
@@ -487,16 +487,12 @@ static int pd_eval_src_caps(struct usbpd *pd, const u32 *src_caps)
 
 static void pd_send_hard_reset(struct usbpd *pd)
 {
-	int ret;
-
 	usbpd_dbg(&pd->dev, "send hard reset");
 
 	/* Force CC logic to source/sink to keep Rp/Rd unchanged */
 	set_power_role(pd, pd->current_pr);
 	pd->hard_reset_count++;
-	ret = pd_phy_signal(HARD_RESET_SIG, 5); /* tHardResetComplete */
-	if (!ret)
-		pd->hard_reset = true;
+	pd_phy_signal(HARD_RESET_SIG, 5); /* tHardResetComplete */
 	pd->in_pr_swap = false;
 }
 
@@ -522,7 +518,7 @@ static void phy_sig_received(struct usbpd *pd, enum pd_sig_type type)
 
 	/* Force CC logic to source/sink to keep Rp/Rd unchanged */
 	set_power_role(pd, pd->current_pr);
-	pd->hard_reset = true;
+	pd->hard_reset_recvd = true;
 	kick_sm(pd, 0);
 }
 
@@ -754,8 +750,6 @@ static void usbpd_set_state(struct usbpd *pd, enum usbpd_state next_state)
 		break;
 
 	case PE_SRC_TRANSITION_TO_DEFAULT:
-		pd->hard_reset = false;
-
 		if (pd->vconn_enabled)
 			regulator_disable(pd->vconn);
 		regulator_disable(pd->vbus);
@@ -1403,7 +1397,7 @@ static void usbpd_sm(struct work_struct *w)
 		pd->in_pr_swap = false;
 		pd->pd_connected = false;
 		pd->in_explicit_contract = false;
-		pd->hard_reset = false;
+		pd->hard_reset_recvd = false;
 		pd->caps_count = 0;
 		pd->hard_reset_count = 0;
 		pd->src_cap_id = 0;
@@ -1456,7 +1450,9 @@ static void usbpd_sm(struct work_struct *w)
 	}
 
 	/* Hard reset? */
-	if (pd->hard_reset) {
+	if (pd->hard_reset_recvd) {
+		pd->hard_reset_recvd = false;
+
 		val.intval = 1;
 		power_supply_set_property(pd->usb_psy,
 				POWER_SUPPLY_PROP_PD_IN_HARD_RESET, &val);
@@ -1829,8 +1825,6 @@ static void usbpd_sm(struct work_struct *w)
 		break;
 
 	case PE_SNK_TRANSITION_TO_DEFAULT:
-		pd->hard_reset = false;
-
 		val.intval = 0;
 		power_supply_set_property(pd->usb_psy,
 				POWER_SUPPLY_PROP_PD_IN_HARD_RESET, &val);
@@ -2117,11 +2111,11 @@ static int psy_changed(struct notifier_block *nb, unsigned long evt, void *ptr)
 		 * During hard reset when VBUS goes to 0 the CC logic
 		 * will report this as a disconnection. In those cases
 		 * it can be ignored, however the downside is that
-		 * pd->hard_reset can be momentarily true even when a
-		 * non-PD capable source is attached, and can't be
-		 * distinguished from a physical disconnect. In that
-		 * case, allow for the common case of disconnecting
-		 * from an SDP.
+		 * we can also happen to be in the SNK_Transition_to_default
+		 * state due to a hard reset attempt even with a non-PD
+		 * capable source, in which a physical disconnect may get
+		 * masked. In that case, allow for the common case of
+		 * disconnecting from an SDP.
 		 *
 		 * The less common case is a PD-capable SDP which will
 		 * result in a hard reset getting treated like a