MFC r331906:

Approved by:	re (gjb)

Fix accidental USB port resets by GPIO on Zynq/Zedboard boards

The Zynq/Zedboard GPIO driver attempts to tri-state all GPIO pins on
boot up but the order in which I reset the hardware can cause the pins
to be briefly held low before being tri-stated.  This is a problem on
boards that use GPIO pins to reset devices.

In particular, the Zybo and ZC-706 boards use a GPIO pin as a USB PHY
reset.  If U-boot enables the USB port before booting the kernel, the
GPIO driver attach causes a glitch on the USB PHY reset and the USB
port loses power.  My fix is to have the GPIO driver leave the pins in
whatever configuration U-boot placed them.

PR:		225713
Submitted by:	Thomas Skibo <thoma555-bsd@yahoo.com>

1 files changed, 0 insertions, 21 deletions

diff --git a/sys/arm/xilinx/zy7_gpio.c b/sys/arm/xilinx/zy7_gpio.c
index 25d22f8..ad2a056 100644
--- a/sys/arm/xilinx/zy7_gpio.c
+++ b/sys/arm/xilinx/zy7_gpio.c
@@ -297,24 +297,6 @@ zy7_gpio_probe(device_t dev)
 	return (0);
 }
 
-static void
-zy7_gpio_hw_reset(struct zy7_gpio_softc *sc)
-{
-	int i;
-
-	for (i = 0; i < NUMBANKS; i++) {
-		WR4(sc, ZY7_GPIO_DATA(i), 0);
-		WR4(sc, ZY7_GPIO_DIRM(i), 0);
-		WR4(sc, ZY7_GPIO_OEN(i), 0);
-		WR4(sc, ZY7_GPIO_INT_DIS(i), 0xffffffff);
-		WR4(sc, ZY7_GPIO_INT_POLARITY(i), 0);
-		WR4(sc, ZY7_GPIO_INT_TYPE(i),
-		    i == 1 ? 0x003fffff : 0xffffffff);
-		WR4(sc, ZY7_GPIO_INT_ANY(i), 0);
-		WR4(sc, ZY7_GPIO_INT_STAT(i), 0xffffffff);
-	}
-}
-
 static int zy7_gpio_detach(device_t dev);
 
 static int
@@ -337,9 +319,6 @@ zy7_gpio_attach(device_t dev)
 		return (ENOMEM);
 	}
 
-	/* Completely reset. */
-	zy7_gpio_hw_reset(sc);
-
 	sc->busdev = gpiobus_attach_bus(dev);
 	if (sc->busdev == NULL) {
 		zy7_gpio_detach(dev);