usb: musb: omap2430: Handle multiple ID ground interrupts

We currently get "unhandled DISCONNECT transition" warnings from musb core
on device disconnect as things are wrongly set to OTG_STATE_A_IDLE in
host mode when enumerating devices. We can also get "Failed to write reg
index" errors after enumerating.

This is happening at least with cpcap phy where we get multiple ID ground
interrupts. Looks like it's VBUS keeps timing out and needs to be kicked
when the phy sends multiple ID ground interrupts during host mode.

Cc: Jacopo Mondi <jacopo@jmondi.org>
Cc: Marcel Partap <mpartap@gmx.net>
Cc: Merlijn Wajer <merlijn@wizzup.org>
Cc: Michael Scott <hashcode0f@gmail.com>
Cc: NeKit <nekit1000@gmail.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Sebastian Reichel <sre@kernel.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Bin Liu <b-liu@ti.com>
Link: https://lore.kernel.org/r/20200115132547.364-7-b-liu@ti.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/musb/omap2430.c

@@ -151,13 +151,26 @@ static void omap_musb_set_mailbox(struct omap2430_glue *glue)
 	switch (glue->status) {
 	case MUSB_ID_GROUND:
 		dev_dbg(musb->controller, "ID GND\n");
-
-		musb->xceiv->otg->state = OTG_STATE_A_IDLE;
-		musb->xceiv->last_event = USB_EVENT_ID;
-		if (musb->gadget_driver) {
-			omap_control_usb_set_mode(glue->control_otghs,
-				USB_MODE_HOST);
+		switch (musb->xceiv->otg->state) {
+		case OTG_STATE_A_WAIT_VRISE:
+		case OTG_STATE_A_WAIT_BCON:
+		case OTG_STATE_A_HOST:
+		case OTG_STATE_A_IDLE:
+			/*
+			 * On multiple ID ground interrupts just keep enabling
+			 * VBUS. At least cpcap VBUS shuts down otherwise.
+			 */
 			omap2430_musb_set_vbus(musb, 1);
+			break;
+		default:
+			musb->xceiv->otg->state = OTG_STATE_A_IDLE;
+			musb->xceiv->last_event = USB_EVENT_ID;
+			if (musb->gadget_driver) {
+				omap_control_usb_set_mode(glue->control_otghs,
+							  USB_MODE_HOST);
+				omap2430_musb_set_vbus(musb, 1);
+			}
+			break;
 		}
 		break;