RK3288 device descriptor read/64, error -32

CPU：RK3288

系统：Android 5.1

主板有两个USB接口，一个接USB摄像头，一个接身份证模块。

插入摄像头可以正常打开，再插入身份证模块时，摄像头就会卡主，而且身份证模块无法识别，内核log如下：

[ 208.492045] usb -1.3: new full-speed USB device number  using usb20_host
[ 208.571251] usb -1.3: device descriptor read/, error -
[ 208.758662] usb -1.3: device descriptor read/, error -
[ 208.945433] usb -1.3: new full-speed USB device number  using usb20_host
[ 209.024159] usb -1.3: device descriptor read/, error -
[ 209.211003] usb -1.3: device descriptor read/, error -
[ 209.398208] usb -1.3: new full-speed USB device number  using usb20_host
[ 209.810731] usb -1.3: device not accepting address , error -
[ 209.890155] usb -1.3: new full-speed USB device number  using usb20_host
[ 210.302863] usb -1.3: device not accepting address , error -
[ 210.303805] hub -:1.0: unable to enumerate USB device on port 

有时可以识别身份证模块，内核log如下：

[  743.983805] usb -1.4: new full-speed USB device number  using usb20_host
[  744.062096] usb -1.4: device descriptor read/, error -
[  744.270232] usb -1.4: New USB device found, idVendor=, idProduct=c35a
[  744.270433] usb -1.4: New USB device strings: Mfr=, Product=, SerialNumber=

出现这种现象的原因是2组USB使用同一路供电，当身份证模块插入时，瞬间拉低了USB电源，导致USB供电不足。

两种解决办法：

1、两组USB单独供电；

2、在USB电源上接一个较大的电容，防止电压瞬间被拉低。