common/usb_pd_protocol: Try.SRC to TryWait.SNK timeout

  The port shall transition to TryWait.SNK after tDRPTry
(75~150ms) and the SRC.Rd state has not been detected and
Vbus is within vSafe0V, or after tTryTimeout(550~1100ms)
and the SRC.Rd state has not been detected. This define
in USB Type-C 1.3 spec section 4.5.2.2.10.2.

BRANCH=None
BUG=None
TEST=GRL USBPD test

Change-Id: I35be7acf24eb360232b1f22a43abb8c1a1dcde99
Signed-off-by: Ruibin Chang <Ruibin.Chang@ite.com.tw>
Reviewed-on: https://chromium-review.googlesource.com/1381592
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Reviewed-by: Daisuke Nojiri <dnojiri@chromium.org>
Reviewed-by: Jett Rink <jettrink@chromium.org>

2 files changed, 51 insertions, 21 deletions

diff --git a/common/usb_pd_protocol.c b/common/usb_pd_protocol.c
index 53b06b800e..72c88c10d4 100644
--- a/common/usb_pd_protocol.c
+++ b/common/usb_pd_protocol.c
@@ -184,6 +184,7 @@ static struct pd_protocol {
 	int prev_request_mv;
 	/* Time for Try.SRC states */
 	uint64_t try_src_marker;
+	uint64_t try_timeout;
 #endif
 
 #ifdef CONFIG_USB_PD_TCPC_LOW_POWER
@@ -2891,32 +2892,58 @@ void pd_task(void *u)
 				pd[port].cc_state = PD_CC_NONE;
 				set_state(port,
 					PD_STATE_SRC_DISCONNECTED_DEBOUNCE);
+				break;
 			}
 #if defined(CONFIG_USB_PD_DUAL_ROLE)
+			now = get_time();
 			/*
-			 * Try.SRC state is embedded here. Wait for SNK
-			 * detect, or if timer expires, transition to
-			 * SNK_DISCONNETED.
-			 *
-			 * If Try.SRC state is not active, then this block
-			 * handles the normal DRP toggle from SRC->SNK
+			 * Try.SRC state is embedded here. The port
+			 * shall transition to TryWait.SNK after
+			 * tDRPTry (PD_T_DRP_TRY) and Vbus is within
+			 * vSafe0V, or after tTryTimeout
+			 * (PD_T_TRY_TIMEOUT). Otherwise we should stay
+			 * within Try.SRC (break).
 			 */
-			else if ((pd[port].flags & PD_FLAGS_TRY_SRC &&
-				 get_time().val >= pd[port].try_src_marker) ||
-				 (!(pd[port].flags & PD_FLAGS_TRY_SRC) &&
-				  drp_state[port] != PD_DRP_FORCE_SOURCE &&
-				  drp_state[port] != PD_DRP_FREEZE &&
-				 get_time().val >= next_role_swap)) {
-				pd_set_power_role(port, PD_ROLE_SINK);
+			if (pd[port].flags & PD_FLAGS_TRY_SRC) {
+				if (now.val < pd[port].try_src_marker) {
+					break;
+				} else if (now.val < pd[port].try_timeout) {
+					if (pd_is_vbus_present(port))
+						break;
+				}
+
+				/*
+				 * Transition to TryWait.SNK now, so set
+				 * state and update src marker time.
+				 */
 				set_state(port, PD_STATE_SNK_DISCONNECTED);
+				pd_set_power_role(port, PD_ROLE_SINK);
 				tcpm_set_cc(port, TYPEC_CC_RD);
-				next_role_swap = get_time().val + PD_T_DRP_SNK;
-				pd[port].try_src_marker = get_time().val
-					+ PD_T_DEBOUNCE;
-
-				/* Swap states quickly */
-				timeout = 2*MSEC;
+				pd[port].try_src_marker =
+					get_time().val + PD_T_DEBOUNCE;
+				timeout = 2 * MSEC;
+				break;
 			}
+
+			/*
+			 * If Try.SRC state is not active, then handle
+			 * the normal DRP toggle from SRC->SNK.
+			 */
+			if (now.val < next_role_swap ||
+			    drp_state[port] == PD_DRP_FORCE_SOURCE ||
+			    drp_state[port] == PD_DRP_FREEZE)
+				break;
+
+			/*
+			 * Transition to SNK now, so set state and
+			 * update next role swap time.
+			 */
+			set_state(port, PD_STATE_SNK_DISCONNECTED);
+			pd_set_power_role(port, PD_ROLE_SINK);
+			tcpm_set_cc(port, TYPEC_CC_RD);
+			next_role_swap = get_time().val + PD_T_DRP_SNK;
+			/* Swap states quickly */
+			timeout = 2 * MSEC;
 #endif
 			break;
 		case PD_STATE_SRC_DISCONNECTED_DEBOUNCE:
@@ -3466,7 +3493,9 @@ void pd_task(void *u)
 				 * then force attempt to connect as source.
 				 */
 				pd[port].try_src_marker = get_time().val
-					+ PD_T_TRY_SRC;
+					+ PD_T_DRP_TRY;
+				pd[port].try_timeout = get_time().val
+					+ PD_T_TRY_TIMEOUT;
 				/* Swap roles to source */
 				pd_set_power_role(port, PD_ROLE_SOURCE);
 				tcpm_set_cc(port, TYPEC_CC_RP);
diff --git a/include/usb_pd.h b/include/usb_pd.h
index ceafd18c9d..f57d8edbb5 100644
--- a/include/usb_pd.h
+++ b/include/usb_pd.h
@@ -176,7 +176,8 @@ enum pd_rx_errors {
 #define PD_T_BIST_TRANSMIT     (50*MSEC) /* 50ms (used for task_wait arg) */
 #define PD_T_BIST_RECEIVE      (60*MSEC) /* 60ms (max time to process bist) */
 #define PD_T_VCONN_SOURCE_ON  (100*MSEC) /* 100ms */
-#define PD_T_TRY_SRC          (125*MSEC) /* Max time for Try.SRC state */
+#define PD_T_DRP_TRY          (125*MSEC) /* btween 75 and 150ms(monitor Vbus) */
+#define PD_T_TRY_TIMEOUT      (550*MSEC) /* between 550ms and 1100ms */
 #define PD_T_TRY_WAIT         (600*MSEC) /* Max time for TryWait.SNK state */
 #define PD_T_SINK_REQUEST     (100*MSEC) /* Wait 100ms before next request */