servo_v4: Don't disable SBU mux when TypeC detach occurs

When a USB PD connection is made, servo_v4 senses the polarity of the
SBU signals and sets the SBU mux for the deteted polarity. If the DUT
is reset, the SBU mux needs to retain the same state so the H1 console
USB endpoint is not disrupted.

Modified the CCD_MODE_DISABLED case to no longer disable the SBU
mux. In addition, removed the static variable ccd_mode as it was being
set, but not ever being checked, so wasn't serving any purpose.

BUG=b:36561120
BRANCH=servo_v4
TEST=Connect servo_v4 to Electro. On Electro EC console enter 'reboot'
verify the H1 USB console remains connected.

Change-Id: I4f0f5167221c04314ca5be063411f200896bbdf6
Signed-off-by: Scott <scollyer@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/464068
Commit-Ready: Scott Collyer <scollyer@chromium.org>
Tested-by: Scott Collyer <scollyer@chromium.org>
Reviewed-by: Mary Ruthven <mruthven@chromium.org>

1 files changed, 12 insertions, 12 deletions

diff --git a/board/servo_v4/board.c b/board/servo_v4/board.c
index b12126c7d8..61271508e7 100644
--- a/board/servo_v4/board.c
+++ b/board/servo_v4/board.c
@@ -304,8 +304,6 @@ static void init_ioexpander(void)
 /* Define voltage thresholds for SBU USB detection */
 #define GND_MAX_MV	350
 #define USB_HIGH_MV	1500
-/* Tracks current state of ccd */
-static int ccd_mode;
 
 static void ccd_measure_sbu(void);
 DECLARE_DEFERRED(ccd_measure_sbu);
@@ -324,16 +322,12 @@ static void ccd_measure_sbu(void)
 		/* SBU flip = 1 */
 		write_ioexpander(0, 2, 1);
 		msleep(10);
-		gpio_set_level(GPIO_SBU_MUX_EN, 1);
-		ccd_mode = CCD_MODE_ENABLED;
 		CPRINTS("CCD: connected flip");
 	} else if ((sbu2 > USB_HIGH_MV) &&
 		   (sbu1 < GND_MAX_MV)) {
 		/* SBU flip = 0 */
 		write_ioexpander(0, 2, 0);
 		msleep(10);
-		gpio_set_level(GPIO_SBU_MUX_EN, 1);
-		ccd_mode = CCD_MODE_ENABLED;
 		CPRINTS("CCD: connected noflip");
 	} else {
 		/* Measure again after 100 msec */
@@ -352,10 +346,12 @@ void ccd_set_mode(enum ccd_mode new_mode)
 
 		/* Disable ccd_measure_sbu deferred call always */
 		hook_call_deferred(&ccd_measure_sbu_data, -1);
-		/* Turn off CCD */
-		gpio_set_level(GPIO_SBU_MUX_EN, 0);
-		CPRINTS("CCD: disconnect");
-		ccd_mode = CCD_MODE_DISABLED;
+		/*
+		 * The DUT port has detected a detach event. Don't want to
+		 * disconnect the SBU mux here so that the H1 USB console can
+		 * remain connected.
+		 */
+		CPRINTS("CCD: TypeC detach, no change to SBU mux");
 	}
 }
 
@@ -382,7 +378,11 @@ static void board_init(void)
 	init_ioexpander();
 	init_uservo_port();
 
-	/* Initialize CCD mode and disable sbu mux. */
-	ccd_set_mode(CCD_MODE_DISABLED);
+	/*
+	 * Enable SBU mux. The polarity is set each time a new PD attach event
+	 * occurs. But, the SBU mux is not disabled on detach so that the H1 USB
+	 * console will survie a DUT EC reset.
+	 */
+	gpio_set_level(GPIO_SBU_MUX_EN, 1);
 }
 DECLARE_HOOK(HOOK_INIT, board_init, HOOK_PRIO_DEFAULT);