usb: hub: make minimum power-on delay configurable

This patch makes the minimum power-on delay for USB HUB
become configurable. The original design waits at least
100 msec here, but some EHCI controlers(e.g. Faraday EHCI)
are known to require much longer delay interval.

Signed-off-by: Kuo-Jung Su <dantesu@faraday-tech.com>
CC: Marek Vasut <marex@denx.de>

README

@@ -1261,6 +1261,9 @@ The following options need to be configured:
 		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
 		txfilltuning field in the EHCI controller on reset.
 
+		CONFIG_USB_HUB_MIN_POWER_ON_DELAY defines the minimum
+		interval for usb hub power-on delay.(minimum 100msec)
+
 - USB Device:
 		Define the below if you wish to use the USB console.
 		Once firmware is rebuilt from a serial console issue the

common/usb_hub.c

@@ -53,6 +53,10 @@
 #include <asm/4xx_pci.h>
 #endif
 
+#ifndef CONFIG_USB_HUB_MIN_POWER_ON_DELAY
+#define CONFIG_USB_HUB_MIN_POWER_ON_DELAY	100
+#endif
+
 #define USB_BUFSIZ	512
 
 static struct usb_hub_device hub_dev[USB_MAX_HUB];
@@ -148,8 +152,8 @@ static void usb_hub_power_on(struct usb_hub_device *hub)
 		debug("port %d returns %lX\n", i + 1, dev->status);
 	}
 
-	/* Wait at least 100 msec for power to become stable */
-	mdelay(max(pgood_delay, (unsigned)100));
+	/* Wait for power to become stable */
+	mdelay(max(pgood_delay, CONFIG_USB_HUB_MIN_POWER_ON_DELAY));
 }
 
 void usb_hub_reset(void)