usb: dwc3: gadget: replace mdelay with udelay in the busy loop

There are two spots where we wait until the HW finishes processing a
certain command. Initially we had a few problems and we used 500ms as a
limit to be on a the safe side. Paul Zimmerman mentioned this is little too
much. After a debugging session, we noticed that we hardly ever go over 20us
and didn't pass 30usec so far. Using mdelay() seems way overloaded.

Giving the current numbers 500usec as the upper limit is more than  enough.
Should it ever timeout then something is definitely wrong.

While here, also replace the type with u32 since long does not really
fit here.

Cc: Paul Zimmerman <paul.zimmerman@synopsys.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/dwc3/gadget.c

@@ -153,7 +153,7 @@ int dwc3_send_gadget_ep_cmd(struct dwc3 *dwc, unsigned ep,
 		unsigned cmd, struct dwc3_gadget_ep_cmd_params *params)
 {
 	struct dwc3_ep		*dep = dwc->eps[ep];
-	unsigned long		timeout = 500;
+	u32			timeout = 500;
 	u32			reg;
 
 	dev_vdbg(dwc->dev, "%s: cmd '%s' params %08x %08x %08x\n",
@@ -175,7 +175,6 @@ int dwc3_send_gadget_ep_cmd(struct dwc3 *dwc, unsigned ep,
 		}
 
 		/*
-		 * XXX Figure out a sane timeout here. 500ms is way too much.
 		 * We can't sleep here, because it is also called from
 		 * interrupt context.
 		 */
@@ -183,7 +182,7 @@ int dwc3_send_gadget_ep_cmd(struct dwc3 *dwc, unsigned ep,
 		if (!timeout)
 			return -ETIMEDOUT;
 
-		mdelay(1);
+		udelay(1);
 	} while (1);
 }
 
@@ -1066,7 +1065,7 @@ static int dwc3_gadget_set_selfpowered(struct usb_gadget *g,
 static void dwc3_gadget_run_stop(struct dwc3 *dwc, int is_on)
 {
 	u32			reg;
-	unsigned long		timeout = 500;
+	u32			timeout = 500;
 
 	reg = dwc3_readl(dwc->regs, DWC3_DCTL);
 	if (is_on)
@@ -1085,13 +1084,10 @@ static void dwc3_gadget_run_stop(struct dwc3 *dwc, int is_on)
 			if (reg & DWC3_DSTS_DEVCTRLHLT)
 				break;
 		}
-		/*
-		 * XXX reduce the 500ms delay
-		 */
 		timeout--;
 		if (!timeout)
 			break;
-		mdelay(1);
+		udelay(1);
 	} while (1);
 
 	dev_vdbg(dwc->dev, "gadget %s data soft-%s\n",