exynos: usb: Fix data abort on boards w/o vbus-gpio node in the DT

Commit 4a271cb1b4 doesn't take into account that fdtdec_setup_gpio()
returns success when the gpio passed to it is FDT_GPIO_NONE (no
gpio node found in the fdtdec_decode_gpio() call). This results in
calling gpio_direction_output() on invalid gpio. For this reason
executing "usb start" command on Arndale causes data abort in the
ehci-exynos driver.

Add the fdt_gpio_isvalid() check to fix that problem.

Signed-off-by: Andrey Konovalov <andrey.konovalov@linaro.org>
Cc: Julius Werner <jwerner@chromium.org>
Cc: Simon Glass <sjg@chromium.org>
Cc: Minkyu Kang <mk7.kang@samsung.com>
Cc: Marek Vasut <marex@denx.de>

drivers/usb/host/ehci-exynos.c

@@ -197,7 +197,8 @@ int ehci_hcd_init(int index, enum usb_init_type init,
 
 #ifdef CONFIG_OF_CONTROL
 	/* setup the Vbus gpio here */
-	if (!fdtdec_setup_gpio(&ctx->vbus_gpio))
+	if (fdt_gpio_isvalid(&ctx->vbus_gpio) &&
+	    !fdtdec_setup_gpio(&ctx->vbus_gpio))
 		gpio_direction_output(ctx->vbus_gpio.gpio, 1);
 #endif
 

drivers/usb/host/xhci-exynos5.c

@@ -298,7 +298,8 @@ int xhci_hcd_init(int index, struct xhci_hccr **hccr, struct xhci_hcor **hcor)
 
 #ifdef CONFIG_OF_CONTROL
 	/* setup the Vbus gpio here */
-	if (!fdtdec_setup_gpio(&ctx->vbus_gpio))
+	if (fdt_gpio_isvalid(&ctx->vbus_gpio) &&
+	    !fdtdec_setup_gpio(&ctx->vbus_gpio))
 		gpio_direction_output(ctx->vbus_gpio.gpio, 1);
 #endif