linux3.8.0 USB2.0 problem

I use linux3.8.0 to add usb2.0 host driver, the cpu is omapl138.

when the board boot, i insert a Kingston 4G USB storage device , the system print some log:

omapl138-lcdk login: root
root@omapl138-lcdk:~# usb 2-1: new high-speed USB device number 2 using musb-hdrc
usb 2-1: New USB device found, idVendor=0951, idProduct=1642
usb 2-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 2-1: Product: DT 101 G2
usb 2-1: Manufacturer: Kingston
usb 2-1: SerialNumber: 0019B92B639ABB20A3DE0118
scsi1 : usb-storage 2-1:1.0
scsi 1:0:0:0: Direct-Access     Kingston DT 101 G2        PMAP PQ: 0 ANSI: 0 CCS
sd 1:0:0:0: [sda] 7831552 512-byte logical blocks: (4.00 GB/3.73 GiB)
sd 1:0:0:0: [sda] Write Protect is off
sd 1:0:0:0: [sda] No Caching mode page present
sd 1:0:0:0: [sda] Assuming drive cache: write through
sd 1:0:0:0: [sda] No Caching mode page present
sd 1:0:0:0: [sda] Assuming drive cache: write through
 sda: sda1
sd 1:0:0:0: [sda] No Caching mode page present
sd 1:0:0:0: [sda] Assuming drive cache: write through
sd 1:0:0:0: [sda] Attached SCSI removable disk

root@omapl138-lcdk:~# usb 2-1: USB disconnect, device number 2

root@omapl138-lcdk:~# 

then i Pull it out  and insert again, the system can't Identify it。

I checked the USB0_DRVVBUS , found it falled to 0V, and never return to 5v.

Here is my code:

static __init void DA850_evm_usb_init(void)
{
	u32 cfgchip2;
	int ret;

	/*
	 * Set up USB clock/mode in the CFGCHIP2 register.
	 * FYI:  CFGCHIP2 is 0x0000ef00 initially.
	 */	

	cfgchip2 = __raw_readl(DA8XX_SYSCFG0_VIRT(DA8XX_CFGCHIP2_REG));

	cfgchip2 &= ~(CFGCHIP2_RESET | CFGCHIP2_PHYPWRDN | CFGCHIP2_OTGPWRDN | 
				  CFGCHIP2_OTGMODE | CFGCHIP2_REFFREQ | CFGCHIP2_USB1PHYCLKMUX);		
	cfgchip2 |= CFGCHIP2_SESENDEN | CFGCHIP2_VBDTCTEN |	CFGCHIP2_PHY_PLLON | 
				CFGCHIP2_REFFREQ_24MHZ | CFGCHIP2_USB2PHYCLKMUX;
	
	cfgchip2 |= CFGCHIP2_FORCE_HOST;

	__raw_writel(cfgchip2, DA8XX_SYSCFG0_VIRT(DA8XX_CFGCHIP2_REG));

	ret = da8xx_register_usb20(1000, 3);
	if (ret)
		pr_warning("%s: USB 2.0 registration failed: %d\n",
			__func__, ret);

	ret = da8xx_register_usb11(&DA850_evm_usb11_pdata);
	if (ret)
		pr_warning("%s: USB 1.1 registration failed: %d\n",
			   __func__, ret);
}

Is anyone can help me? Thanks in advance!