usb: musb: omap2430: don't loop indefinitely in interrupt.

When called during resume_irqs, omap2430_musb_set_vbus() is run with
interrupts disabled,  In that case 'jiffies' never changes so the loop
can loop forever.

So impose a maximum loop count and add an 'mdelay' to ensure we wait
a reasonable amount of time for bit to be cleared.

This fixes a hang on resume.
Signed-of-by: NeilBrown <neilb@suse.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/musb/omap2430.c

@@ -34,6 +34,7 @@
 #include <linux/dma-mapping.h>
 #include <linux/pm_runtime.h>
 #include <linux/err.h>
+#include <linux/delay.h>
 #include <linux/usb/musb-omap.h>
 
 #include "musb_core.h"
@@ -150,6 +151,7 @@ static void omap2430_musb_set_vbus(struct musb *musb, int is_on)
 
 	if (is_on) {
 		if (musb->xceiv->state == OTG_STATE_A_IDLE) {
+			int loops = 100;
 			/* start the session */
 			devctl |= MUSB_DEVCTL_SESSION;
 			musb_writeb(musb->mregs, MUSB_DEVCTL, devctl);
@@ -159,9 +161,11 @@ static void omap2430_musb_set_vbus(struct musb *musb, int is_on)
 			 */
 			while (musb_readb(musb->mregs, MUSB_DEVCTL) & 0x80) {
 
+				mdelay(5);
 				cpu_relax();
 
-				if (time_after(jiffies, timeout)) {
+				if (time_after(jiffies, timeout)
+				    || loops-- <= 0) {
 					dev_err(musb->controller,
 					"configured as A device timeout");
 					ret = -EINVAL;