eve: Delay charge port selection until VBUS is stable or 1s has passed

When a charge port is selected and VBUS is 5V, the inrush current causes
VBUS to droop which could signal a sink disconnection.

To mitigate this problem, charge port selection is delayed until VBUS
is stable or 1s has passed. Before 1s has passed, PD will hopefully have
negotiated a VBUS voltage of at least 9V.

This CL is also a workaround for the issue outlined in b:74753447

Signed-off-by: Sam Hurst <shurst@chromium.org>

BUG=b:69439094
BRANCH=None
TEST=`make -j buildall`
Manual tested with Belkin Express Dock and Moshi audio adapter.
Test Belkin with following configuration:

PORT0:    PORT1:
Belkin    OPEN
OPEN      Belkin
Belkin    Blackcat
Blackcat  Belkin

Belkin EC terminal output:
Port 0:
[654.645288 TCPC p0 Exit Low Power Mode]
C0 st14
C0 st15
C0 st17
C0 st18
C0 st19
Requested 5000 V 3000 mA (for 900/900 mA)
C0 st20
C0 st21
C0 st22
C0 st23
C0 st24
C0 st23
C0 st26
C0 st27
C0 st28
C0 st29
[655.375668 New chg p0]
C0 st5
[655.380708 Ramp reset: st1]
[655.381704 CL: p0 s8 i500 v5000]
[655.392598 New chg p0]
[655.393574 Ramp reset: st1]
[655.394504 CL: p0 s2 i3000 v5000]
C0 Req [4] 15000mV 3000mA
[655.512126 New chg p0]
[655.514456 Ramp reset: st1]
C0 st715219 CL: p0 s0 ]
C0 st8
[655.639762 Ramp reset: st1]
[655.640301 CL: p0 s0 i3000 v15000]
[656.688735 AC on]
[657.385539 Ramp p0 st5 3000mA 3000mA]
[657.471108 Battery 70% / 7h:36 to empty]
[659.721858 charge_request(8800mV, 5376mA)]
[660.973258 charge_request(8800mV, 3712mA)]
[697.506594 Battery 71% / 1h:1 to full]

Port 1:
[729.384242 TCPC p1 Exit Low Power Mode]
C1 st2
C1 st3
C1 st14
C1 st15
C1 st17
C1 st18
C1 st19
Requested 5000 V 3000 mA (for 900/900 mA)
C1 st20
C1 st21
C1 st22
C1 st23
C1 st24
C1 st23
C1 st26
C1 st27
C1 st28
C1 st29
[730.339719 New chg p1]
[730.340602 Ramp reset: st1]
[C1 st5
730.341457 CL: p1 s8 i500 v5000]
[730.356552 New chg p1]
[730.357311 Ramp reset: st1]
[730.358095 CL: p1 s2 i3000 v5000]
C1 Req [4] 15000mV 3000mA
[730.478577 New chg p1]
[730.480986 Ramp reset: st1]
[730.481829 CL:Cp1 s0 i500 v15]
C1 st8
[730.607116 Ramp reset: st1]
[730.607813 CL: p1 s0 i3000 v15000]
[731.654877 AC on]
[732.345420 Ramp p1 st5 3000mA 3000mA]
[732.589802 Battery 71% / 10h:28 to empty]
[734.340030 charge_request(8800mV, 5376mA)]
[735.091263 charge_request(8800mV, 3712mA)]
[767.879314 Battery 72% / 1h:1 to full]

Tested Moshi with followint configuration:

Port0:           Port1:
Moshi-pwr        OPEN
OPEN             Moshi-pwr
Moshi-pwr        Blackcat
Blackcat         Moshi-pwr
Moshi-audio      OPEN
OPEN             Moshi-audio
Moshi-audio      Blackcat
Blackcat         Moshi-pwr
Moshi-pwr-audio  OPEN
OPEN             Moshi-pwr-audio
Moshi-pwr-audio  Blackcat
Blackcat         Moshi-pwr-audio

Moshi EC terminal output:

[2330.883267 TCPC p0 Low Power Mode]
[2330.883664 TCPC p0 reset!]
[2330.916049 TCPC p0 Low Power Mode]
[2330.916475 TCPC p0 reset!]
[2330.934010 TCPC p0 Exit Low Power Mode]
C0 st14
C0 st15
C0 st17
C0 st18
C0 st19
Requested 5000 V 3000 mA (for 3000/3000 mA)
C0 st20
C0 st21
C0 st22
C0 st23
C0 st24
C0 st23
C0 st26
C0 st23
C0 st27
C0 st28
C0 st29
[2332.398132 New chg p0]
[2332.398883 Ramp reset: st1]
[2332.399745 CL: p0 s8 i500 v5000]
C0 st5
[2332.476132 New chg p0]
[2332.476933 Ramp reset: st1]
[2332.477705 CL: p0 s2 i3000 v5000]
C0 Req [4] 15000mV 2970mA
[2332.493597 New cCg p0C0 st7
]
[2332[2332.5001C0 st8
[2332.674727 Ramp reset: st1]
[2332.675510 CL: p0 s0 i2970 v15000]
[2333.668216 AC on]
[2334.403481 Ramp p0 st5 2970mA 2970mA]
[2334.450155 Battery 80% / 11h:18 to empty]
[2335.448877 charge_request(8800mV, 5376mA)]
[2336.699875 charge_request(8800mV, 3712mA)]
[2356.466385 Battery 81% / 1h:1 to full]

Change-Id: Iba909c252094c0e5ca4cf974aabcfe1eaf002efd
Reviewed-on: https://chromium-review.googlesource.com/1157554
Reviewed-by: Duncan Laurie <dlaurie@google.com>
Commit-Queue: Duncan Laurie <dlaurie@google.com>
Tested-by: Duncan Laurie <dlaurie@google.com>

3 files changed, 125 insertions, 0 deletions

diff --git a/board/eve/board.h b/board/eve/board.h
index 7441b07d39..05cdba3cdb 100644
--- a/board/eve/board.h
+++ b/board/eve/board.h
@@ -167,6 +167,7 @@
 #define CONFIG_USB_PD_DISCHARGE_TCPC
 #define CONFIG_USB_PD_DUAL_ROLE
 #define CONFIG_USB_PD_DUAL_ROLE_AUTO_TOGGLE
+#define CONFIG_BD9995X_DELAY_INPUT_PORT_SELECT
 #define CONFIG_USB_PD_LOGGING
 #define CONFIG_USB_PD_LOG_SIZE 512
 #define CONFIG_USB_PD_MAX_SINGLE_SOURCE_CURRENT TYPEC_RP_3A0
diff --git a/driver/charger/bd9995x.c b/driver/charger/bd9995x.c
index c43549900c..39af5c9d86 100644
--- a/driver/charger/bd9995x.c
+++ b/driver/charger/bd9995x.c
@@ -35,6 +35,37 @@
 /* Console output macros */
 #define CPRINTS(format, args...) cprints(CC_CHARGER, format, ## args)
 
+#ifdef CONFIG_BD9995X_DELAY_INPUT_PORT_SELECT
+/*
+ * Used in a check to determine if VBUS is within the
+ * range of some VOLTAGE +/- VBUS_DELTA, where voltage
+ * is measured in mV.
+ */
+#define VBUS_DELTA 1000
+
+/* VBUS is debounced if it's stable for this length of time */
+#define VBUS_MSEC (100*MSEC)
+
+/* VBUS debouncing sample interval */
+#define VBUS_CHECK_MSEC (10*MSEC)
+
+/* Time to wait before VBUS debouncing begins */
+#define STABLE_TIMEOUT (500*MSEC)
+
+/* Maximum time to wait until VBUS is debounced */
+#define DEBOUNCE_TIMEOUT (500*MSEC)
+
+enum vstate {START, STABLE, DEBOUNCE};
+static enum vstate vbus_state;
+
+static int vbus_voltage;
+static uint64_t debounce_time;
+static uint64_t vbus_timeout;
+static int port_update;
+static int select_update;
+static int select_input_port_update;
+#endif
+
 /* Charger parameters */
 static const struct charger_info bd9995x_charger_info = {
 	.name         = CHARGER_NAME,
@@ -1048,7 +1079,12 @@ int bd9995x_is_vbus_provided(enum bd9995x_charge_port port)
 	return !!reg;
 }
 
+#ifdef CONFIG_BD9995X_DELAY_INPUT_PORT_SELECT
+static int bd9995x_select_input_port_private(enum bd9995x_charge_port port,
+								int select)
+#else
 int bd9995x_select_input_port(enum bd9995x_charge_port port, int select)
+#endif
 {
 	int rv;
 	int reg;
@@ -1093,6 +1129,49 @@ select_input_port_exit:
 	return rv;
 }
 
+#ifdef CONFIG_BD9995X_DELAY_INPUT_PORT_SELECT
+int bd9995x_select_input_port(enum bd9995x_charge_port port, int select)
+{
+	port_update = port;
+	select_update = select;
+	vbus_state = START;
+	select_input_port_update = 1;
+	task_wake(TASK_ID_USB_CHG);
+
+	return EC_SUCCESS;
+}
+
+static inline int bd9995x_vbus_test(int value, int limit)
+{
+	uint32_t hi_value = limit + VBUS_DELTA;
+	uint32_t lo_value = limit - VBUS_DELTA;
+
+	return ((value > lo_value) && (value < hi_value));
+}
+
+static int bd9995x_vbus_debounce(enum bd9995x_charge_port port)
+{
+	int vbus_reg;
+	int voltage;
+
+	vbus_reg = (port == BD9995X_CHARGE_PORT_VBUS) ?
+		BD9995X_CMD_VBUS_VAL : BD9995X_CMD_VCC_VAL;
+	if (ch_raw_read16(vbus_reg, &voltage, BD9995X_EXTENDED_COMMAND))
+		voltage = 0;
+
+	if (!bd9995x_vbus_test(voltage, vbus_voltage)) {
+		vbus_voltage = voltage;
+		debounce_time = get_time().val + VBUS_MSEC;
+	} else {
+		if (get_time().val >= debounce_time)
+			return 1;
+	}
+
+	return 0;
+}
+#endif
+
+
 #ifdef CONFIG_CHARGER_BATTERY_TSENSE
 int bd9995x_get_battery_temp(int *temp_ptr)
 {
@@ -1192,6 +1271,11 @@ void usb_charger_task(void *u)
 	int vbus_reg, voltage;
 #endif
 
+#ifdef CONFIG_BD9995X_DELAY_INPUT_PORT_SELECT
+	select_input_port_update = 0;
+	vbus_voltage = 0;
+#endif
+
 	for (port = 0; port < CONFIG_USB_PD_PORT_COUNT; port++) {
 		bc12_detected_type[port] = CHARGE_SUPPLIER_NONE;
 		bd9995x_enable_vbus_detect_interrupts(port, 1);
@@ -1269,6 +1353,43 @@ void usb_charger_task(void *u)
 		}
 
 		initialized = 1;
+#ifdef CONFIG_BD9995X_DELAY_INPUT_PORT_SELECT
+/*
+ * When a charge port is selected and VBUS is 5V, the inrush current on some
+ * devices causes VBUS to droop, which could signal a sink disconnection.
+ *
+ * To mitigate the problem, charge port selection is delayed until VBUS
+ * is stable or one second has passed. Hopefully PD has negotiated a VBUS
+ * voltage of at least 9V before the one second timeout.
+ */
+	if (select_input_port_update) {
+		sleep_usec = VBUS_CHECK_MSEC;
+		changed = 0;
+
+		switch (vbus_state) {
+		case START:
+			vbus_timeout = get_time().val + STABLE_TIMEOUT;
+			vbus_state = STABLE;
+			break;
+		case STABLE:
+			if (get_time().val > vbus_timeout) {
+				vbus_state = DEBOUNCE;
+				vbus_timeout = get_time().val +
+							DEBOUNCE_TIMEOUT;
+			}
+			break;
+		case DEBOUNCE:
+			if (bd9995x_vbus_debounce(port_update) ||
+					get_time().val > vbus_timeout) {
+				select_input_port_update = 0;
+				bd9995x_select_input_port_private(
+						port_update, select_update);
+			}
+			break;
+		}
+	}
+#endif
+
 		/*
 		 * Re-read interrupt registers immediately if we got an
 		 * interrupt. We're dealing with multiple independent
diff --git a/include/config.h b/include/config.h
index 415cba7b21..83472a7c5a 100644
--- a/include/config.h
+++ b/include/config.h
@@ -2371,6 +2371,9 @@
 /* Define if this board can used TCPC-controlled DRP toggle */
 #undef CONFIG_USB_PD_DUAL_ROLE_AUTO_TOGGLE
 
+/* Define to reduces VBUS droop caused by inrush current during charging */
+#undef CONFIG_BD9995X_DELAY_INPUT_PORT_SELECT
+
 /* Initial DRP / toggle policy */
 #define CONFIG_USB_PD_INITIAL_DRP_STATE PD_DRP_TOGGLE_OFF