usb: legacy_hub_port_reset(): Speedup hub reset handling

Start with a short USB hub reset delay of 20ms. This can be enough for
some configurations.

The 2nd delay at the end of the loop is completely removed. Since the
delay hasn't been long enough, a longer delay time of 200ms is assigned
and will be used in the next loop round.

This hub reset handling is also used in the v4.4 Linux USB driver,
hub_port_reset().

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Simon Glass <sjg@chromium.org>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Tested-by: Stephen Warren <swarren@nvidia.com>
Cc: Marek Vasut <marex@denx.de>

common/usb_hub.c

@@ -46,6 +46,9 @@ DECLARE_GLOBAL_DATA_PTR;
 
 #define USB_BUFSIZ	512
 
+#define HUB_SHORT_RESET_TIME	20
+#define HUB_LONG_RESET_TIME	200
+
 /* TODO(sjg@chromium.org): Remove this when CONFIG_DM_USB is defined */
 static struct usb_hub_device hub_dev[USB_MAX_HUB];
 static int usb_hub_index;
@@ -164,6 +167,7 @@ int legacy_hub_port_reset(struct usb_device *dev, int port,
 	int err, tries;
 	ALLOC_CACHE_ALIGN_BUFFER(struct usb_port_status, portsts, 1);
 	unsigned short portstatus, portchange;
+	int delay = HUB_SHORT_RESET_TIME; /* start with short reset delay */
 
 #ifdef CONFIG_DM_USB
 	debug("%s: resetting '%s' port %d...\n", __func__, dev->dev->name,
@@ -176,7 +180,7 @@ int legacy_hub_port_reset(struct usb_device *dev, int port,
 		if (err < 0)
 			return err;
 
-		mdelay(200);
+		mdelay(delay);
 
 		if (usb_get_port_status(dev, port + 1, portsts) < 0) {
 			debug("get_port_status failed status %lX\n",
@@ -215,7 +219,8 @@ int legacy_hub_port_reset(struct usb_device *dev, int port,
 		if (portstatus & USB_PORT_STAT_ENABLE)
 			break;
 
-		mdelay(200);
+		/* Switch to long reset delay for the next round */
+		delay = HUB_LONG_RESET_TIME;
 	}
 
 	if (tries == MAX_TRIES) {