Revert "ServoV4/V4p1: Change CCD detection flow"

This reverts commit 1a09ade7b846cc048fb2f177adcacd5f836b8887.

Reason for revert: b:167734179 CCD detection is failing on many devices. Tests on reverted devices show this is primary cause.

Original change's description:
> ServoV4/V4p1: Change CCD detection flow
>
> Currently, servoV4 and servoV4p1 don't apply terminations to SBU when
> searching for a DUT. This means SBU can float which can break the SBU
> voltage detection. Technically, the DUT should only need to pull up D+
> and can float D- since it is a FS USB2 device when in CCD mode.
>
> Change the detection to connect SBU to the USB2 hub on servoV4/4p1. The
> USB2 hub will apply 15k pulldowns to the USB lines, which will pull SBU
> down and fix detection in the case where the DUT floats SBU.
>
> BUG=b:161762948, b:150886157, b:151487379
> TEST=make BOARD=servo_v4; make BOARD=servo_v4p1
> TEST=check that CCD works on DUT without pulldown resistors on SBU
> BRANCH=none
>
> Change-Id: I9b6f620617fb0e270e35804704111afd3c606a3b
> Signed-off-by: Eric Herrmann <eherrmann@chromium.org>
> Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2352439
> Reviewed-by: Wai-Hong Tam <waihong@google.com>

BUG=b:167734179, b:168546666, b:168548776
TEST=Measured SBU voltages with the prior CL included, observed
  low voltages and no-voltage on some platforms including variations
  of dedede under the flipped orientation.
TEST=Reverted the CL and CCD detection worked reliably,
  devices with CCD not driving SBU rails started working, and
  labstation release was more reliable on prior versions.

Change-Id: Iaecd7371164804ce09a7fd19ac8fd1f44d93aef2
Signed-off-by: Brian Nemec <bnemec@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2429496
Reviewed-by: Wai-Hong Tam <waihong@google.com>
Reviewed-by: Eric Herrmann <eherrmann@chromium.org>

1 files changed, 25 insertions, 25 deletions

diff --git a/board/servo_v4/board.c b/board/servo_v4/board.c
index 8d78301a6d..fc6735e19c 100644
--- a/board/servo_v4/board.c
+++ b/board/servo_v4/board.c
@@ -366,8 +366,6 @@ static void init_ioexpander(void)
 	 */
 	i2c_write8(1, GPIOX_I2C_ADDR_FLAGS, GPIOX_DIR_PORT_A, 0x0);
 	i2c_write8(1, GPIOX_I2C_ADDR_FLAGS, GPIOX_DIR_PORT_B, 0x18);
-	/* Write SBU_FLIP_SEL */
-	write_ioexpander(0, 2, 0);
 }
 
 /*
@@ -392,27 +390,24 @@ static void ccd_measure_sbu(void)
 {
 	int sbu1;
 	int sbu2;
+	int mux_en;
 	static int count /* = 0 */;
 	static int last /* = 0 */;
 	static int polarity /* = 0 */;
 
-	/*
-	 * The SBU mux should be enabled so SBU is connected to the USB2
-	 * hub. The hub needs to apply its terminations to read the
-	 * correct SBU levels.
-	 */
-	gpio_set_level(GPIO_SBU_MUX_EN, 1);
-
 	/* Read sbu voltage levels */
 	sbu1 = adc_read_channel(ADC_SBU1_DET);
 	sbu2 = adc_read_channel(ADC_SBU2_DET);
+	mux_en = gpio_get_level(GPIO_SBU_MUX_EN);
 
 	/*
-	 * Poll the SBU lines to check if an idling, unconfigured USB device is
-	 * present. USB FS pulls one line high for connect request. If so, and
-	 * it persists for 500ms, we'll enable the SuzyQ in that orientation.
+	 * While SBU_MUX is disabled (SuzyQ unplugged), we'll poll the SBU lines
+	 * to check if an idling, unconfigured USB device is present.
+	 * USB FS pulls one line high for connect request.
+	 * If so, and it persists for 500ms, we'll enable the SuzyQ in that
+	 * orientation.
 	 */
-	if ((sbu1 > USB_HIGH_MV) && (sbu2 < GND_MAX_MV)) {
+	if ((!mux_en) && (sbu1 > USB_HIGH_MV) && (sbu2 < GND_MAX_MV)) {
 		/* Check flip connection polarity. */
 		if (last != MODE_SBU_FLIP) {
 			last = MODE_SBU_FLIP;
@@ -421,7 +416,7 @@ static void ccd_measure_sbu(void)
 		} else {
 			count++;
 		}
-	} else if ((sbu2 > USB_HIGH_MV) && (sbu1 < GND_MAX_MV)) {
+	} else if ((!mux_en) && (sbu2 > USB_HIGH_MV) && (sbu1 < GND_MAX_MV)) {
 		/* Check direct connection polarity. */
 		if (last != MODE_SBU_CONNECT) {
 			last = MODE_SBU_CONNECT;
@@ -431,14 +426,12 @@ static void ccd_measure_sbu(void)
 			count++;
 		}
 	/*
-	 * If SuzyQ is enabled, we'll poll for a persistent no-signal
-	 * for 500ms. We may see GND/GND while passing data since the
-	 * ADC's don't sample simultaneously, so there needs to be a
-	 * deglitch to not falsely detect a disconnect. If disconnected,
-	 * take no action. We need to keep the mux enabled to detect
-	 * another device.
+	 * If SuzyQ is enabled, we'll poll for a persistent no-signal for
+	 * 500ms. Since USB is differential, we should never see GND/GND
+	 * while the device is connected.
+	 * If disconnected, electrically remove SuzyQ.
 	 */
-	} else if ((sbu1 < GND_MAX_MV) && (sbu2 < GND_MAX_MV)) {
+	} else if ((mux_en) && (sbu1 < GND_MAX_MV) && (sbu2 < GND_MAX_MV)) {
 		/* Check for SBU disconnect if connected. */
 		if (last != MODE_SBU_DISCONNECT) {
 			last = MODE_SBU_DISCONNECT;
@@ -456,24 +449,31 @@ static void ccd_measure_sbu(void)
 	 * We have seen a new state continuously for 500ms.
 	 * Let's update the mux to enable/disable SuzyQ appropriately.
 	 */
-	if (count == 50) {
-		if (last == MODE_SBU_DISCONNECT) {
+	if (count > 5) {
+		if (mux_en) {
+			/* Disable mux as it's disconnected now. */
+			gpio_set_level(GPIO_SBU_MUX_EN, 0);
+			msleep(10);
 			CPRINTS("CCD: disconnected.");
 		} else {
 			/* SBU flip = polarity */
 			write_ioexpander(0, 2, polarity);
+			gpio_set_level(GPIO_SBU_MUX_EN, 1);
+			msleep(10);
 			CPRINTS("CCD: connected %s",
 				polarity ? "flip" : "noflip");
 		}
 	}
-	/* Measure every 10ms, forever. */
-	hook_call_deferred(&ccd_measure_sbu_data, 10 * MSEC);
+
+	/* Measure every 100ms, forever. */
+	hook_call_deferred(&ccd_measure_sbu_data, 100 * MSEC);
 }
 
 void ext_hpd_detection_enable(int enable)
 {
 	if (enable) {
 		timestamp_t now = get_time();
+
 		hpd_prev_level = gpio_get_level(GPIO_DP_HPD);
 		hpd_prev_ts = now.val;
 		gpio_enable_interrupt(GPIO_DP_HPD);