pd: refactor disconnection detection

Verify the connection status at every FSM loop,
by monitoring VBUS presence for the sink and by monitoring CC going
above Vnc for the source.

Also ensure we are never stuck in the source transition state in the
sink doesn't ack the PSReady packet.

Signed-off-by: Vincent Palatin <vpalatin@chromium.org>

BRANCH=none
BUG=none
TEST=connect Firefly to Zinger, trigger hundreds of voltage transition,
record and analyze the PD traffic : no longer see spurious PSReady
messages.

Change-Id: I4495ae5415d53d77055fb2a562c594fa9a1d4dc8
Reviewed-on: https://chromium-review.googlesource.com/206945
Tested-by: Vincent Palatin <vpalatin@chromium.org>
Reviewed-by: Alec Berg <alecaberg@chromium.org>
Tested-by: Alec Berg <alecaberg@chromium.org>
Commit-Queue: Vincent Palatin <vpalatin@chromium.org>

1 files changed, 28 insertions, 30 deletions

diff --git a/common/usb_pd_protocol.c b/common/usb_pd_protocol.c
index d5bda7c6f3..68de8f4ee0 100644
--- a/common/usb_pd_protocol.c
+++ b/common/usb_pd_protocol.c
@@ -829,16 +829,6 @@ void pd_task(void)
 			timeout = 10*MSEC;
 			break;
 		case PD_STATE_SRC_DISCOVERY:
-			/* Detect disconnect by monitoring Vnc */
-			cc1_volt = pd_adc_read(pd_polarity);
-			if (cc1_volt > PD_SRC_VNC) {
-				/* The sink disappeared ... */
-				pd_power_supply_reset();
-				pd_task_state = PD_STATE_SRC_DISCONNECTED;
-				/* Debouncing */
-				timeout = 50*MSEC;
-				break;
-			}
 			/* Query capabilites of the other side */
 			res = send_source_cap(ctxt);
 			/* packet was acked => PD capable device) */
@@ -850,6 +840,7 @@ void pd_task(void)
 			break;
 		case PD_STATE_SRC_NEGOCIATE:
 			/* wait for a "Request" message */
+			timeout = 500*MSEC;
 			break;
 		case PD_STATE_SRC_ACCEPTED:
 			/* Accept sent, wait for the end of transition */
@@ -865,8 +856,11 @@ void pd_task(void)
 				timeout =  PD_T_SEND_SOURCE_CAP;
 				/* it'a time to ping regularly the sink */
 				pd_task_state = PD_STATE_SRC_READY;
+			} else {
+				/* The sink did not ack, cut the power... */
+				pd_power_supply_reset();
+				pd_task_state = PD_STATE_SRC_DISCOVERY;
 			}
-			/* TODO error fallback */
 			break;
 		case PD_STATE_SRC_READY:
 			/* Verify that the sink is alive */
@@ -912,16 +906,6 @@ void pd_task(void)
 			timeout = 10*MSEC;
 			break;
 		case PD_STATE_SNK_DISCOVERY:
-			/* For non-PD aware source, detect source disconnect */
-			cc1_volt = pd_adc_read(pd_polarity);
-			if (cc1_volt < PD_SNK_VA) {
-				/* The source disappeared ... */
-				pd_task_state = PD_STATE_SNK_DISCONNECTED;
-				/* Debouncing */
-				timeout = 50*MSEC;
-				break;
-			}
-
 			/* Don't continue if power negotiation is not allowed */
 			if (!pd_power_negotiation_allowed()) {
 				timeout = PD_T_GET_SOURCE_CAP;
@@ -963,15 +947,6 @@ void pd_task(void)
 			 */
 			pd_charger_change(1);
 #endif
-
-			/* if we have lost vbus, go back to disconnected */
-			if (!pd_snk_is_vbus_provided()) {
-				pd_task_state = PD_STATE_SNK_DISCONNECTED;
-				/* set timeout small to reconnect fast */
-				timeout = 5*MSEC;
-				break;
-			}
-
 			/* check vital parameters from time to time */
 			timeout = 100*MSEC;
 			break;
@@ -986,6 +961,29 @@ void pd_task(void)
 			bist_mode_2_rx();
 			break;
 		}
+
+		/* Check for disconnection */
+		if (pd_role == PD_ROLE_SOURCE &&
+		    pd_task_state != PD_STATE_SRC_DISCONNECTED) {
+			/* Source: detect disconnect by monitoring CC */
+			cc1_volt = pd_adc_read(pd_polarity);
+			if (cc1_volt > PD_SRC_VNC) {
+				pd_power_supply_reset();
+				pd_task_state = PD_STATE_SRC_DISCONNECTED;
+				/* Debouncing */
+				timeout = 50*MSEC;
+			}
+		}
+#ifdef CONFIG_USB_PD_DUAL_ROLE
+		if (pd_role == PD_ROLE_SINK &&
+		    pd_task_state != PD_STATE_SNK_DISCONNECTED &&
+		    !pd_snk_is_vbus_provided()) {
+			/* Sink: detect disconnect by monitoring VBUS */
+			pd_task_state = PD_STATE_SNK_DISCONNECTED;
+			/* set timeout small to reconnect fast */
+			timeout = 5*MSEC;
+		}
+#endif /* CONFIG_USB_PD_DUAL_ROLE */
 	}
 }