pd: Ensure TCPC exits low power mode

Ensure the TCPC is awake when leaving PD_STATE_DRP_AUTO_TOGGLE and
when there is a new PD event to handle.

Move the exit_low_power_mode() call from the PD_STATE_DRP_AUTO_TOGGLE
case statement into set_state(), to catch all possible paths that
exit the state.

Add a new exit_low_power_mode() call to the top of the main task loop
if there is a new event to handle. This allows the exit_low_power_mode()
call to be removed from pd_update_dual_role_config() (since
PD_EVENT_UPDATE_DUAL_ROLE is included in PD_EXIT_LOW_POWER_EVENT_MASK).

Clear PD_FLAGS_LPM_REQUESTED when PD_FLAGS_LPM_ENGAGED is cleared in
handle_device_access() and wake the PD task to ensure we will make
another pass through the main task loop (and check the CC lines)
before deciding to enter low power mode again.

BRANCH=none
BUG=b:111663127,b:112039224
TEST=PD and TCPC low power still work on Grunt

Change-Id: I99063ce0d02af65de74f4c6f73f7a15600d2eac9
Signed-off-by: Edward Hill <ecgh@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1225352
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Reviewed-by: Jett Rink <jettrink@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1231361
Reviewed-by: Martin Roth <martinroth@chromium.org>
Commit-Queue: Martin Roth <martinroth@chromium.org>
Tested-by: Martin Roth <martinroth@chromium.org>

2 files changed, 22 insertions, 12 deletions

diff --git a/common/usb_pd_protocol.c b/common/usb_pd_protocol.c
index 9db2510ca3..1a13b4d710 100644
--- a/common/usb_pd_protocol.c
+++ b/common/usb_pd_protocol.c
@@ -374,8 +374,14 @@ static void handle_device_access(int port)
 
 	pd[port].low_power_time = get_time().val + PD_LPM_DEBOUNCE_US;
 	if (pd[port].flags & PD_FLAGS_LPM_ENGAGED) {
-		CPRINTS("TCPC p%d Exited Low Power Mode via bus access", port);
-		pd[port].flags &= ~PD_FLAGS_LPM_ENGAGED;
+		CPRINTS("TCPC p%d Exit Low Power Mode", port);
+		pd[port].flags &= ~(PD_FLAGS_LPM_ENGAGED |
+				    PD_FLAGS_LPM_REQUESTED);
+		/*
+		 * Wake to ensure we make another pass through the main task
+		 * loop after clearing the flags.
+		 */
+		task_wake(PD_PORT_TO_TASK_ID(port));
 	}
 }
 
@@ -560,6 +566,11 @@ static inline void set_state(int port, enum pd_states next_state)
 	if (last_state == next_state)
 		return;
 
+#ifdef CONFIG_USB_PD_TCPC_LOW_POWER
+	if (next_state != PD_STATE_DRP_AUTO_TOGGLE)
+		exit_low_power_mode(port);
+#endif
+
 #ifdef CONFIG_USB_PD_DUAL_ROLE
 #ifdef CONFIG_USB_PD_DUAL_ROLE_AUTO_TOGGLE
 	/* Clear flag to allow DRP auto toggle when possible */
@@ -2124,11 +2135,6 @@ static void pd_update_dual_role_config(int port)
 		set_state(port, PD_STATE_SRC_DISCONNECTED);
 		tcpm_set_cc(port, TYPEC_CC_RP);
 	}
-
-#ifdef CONFIG_USB_PD_TCPC_LOW_POWER
-	/* When switching drp mode, make sure tcpc is out of standby mode */
-	exit_low_power_mode(port);
-#endif
 }
 
 int pd_get_role(int port)
@@ -2593,6 +2599,8 @@ void pd_task(void *u)
 		evt = task_wait_event(timeout);
 
 #ifdef CONFIG_USB_PD_TCPC_LOW_POWER
+		if (evt & PD_EXIT_LOW_POWER_EVENT_MASK)
+			exit_low_power_mode(port);
 		if (evt & PD_EVENT_DEVICE_ACCESSED)
 			handle_device_access(port);
 #endif
@@ -3812,11 +3820,6 @@ void pd_task(void *u)
 				/* Anything else, keep toggling */
 				next_state = PD_STATE_DRP_AUTO_TOGGLE;
 
-#ifdef CONFIG_USB_PD_TCPC_LOW_POWER
-			if (next_state != PD_STATE_DRP_AUTO_TOGGLE)
-				exit_low_power_mode(port);
-#endif
-
 			if (next_state == PD_STATE_SNK_DISCONNECTED) {
 				tcpm_set_cc(port, TYPEC_CC_RD);
 				pd_set_power_role(port, PD_ROLE_SINK);
diff --git a/include/usb_pd.h b/include/usb_pd.h
index 29299b8acf..76970cb044 100644
--- a/include/usb_pd.h
+++ b/include/usb_pd.h
@@ -49,6 +49,13 @@ enum pd_rx_errors {
 #define PD_EVENT_DEVICE_ACCESSED    (1<<7)
 #define PD_EVENT_POWER_STATE_CHANGE (1<<8) /* Chipset power state changed */
 
+/* Ensure TCPC is out of low power mode before handling these events. */
+#define PD_EXIT_LOW_POWER_EVENT_MASK \
+	(PD_EVENT_CC | \
+	 PD_EVENT_UPDATE_DUAL_ROLE | \
+	 PD_EVENT_POWER_STATE_CHANGE | \
+	 TASK_EVENT_WAKE)
+
 /* --- PD data message helpers --- */
 #define PDO_MAX_OBJECTS   7
 #define PDO_MODES (PDO_MAX_OBJECTS - 1)