Other Parts Discussed in Thread: AM3351
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器件型号： AM3351
尝试在基于 AM335x 的定制电路板上启动 USB。 USB 端口在未连接器件的情况下锁存在“oc suspend“状态。该设计不连接 USB0_VBUS 以进行隔离。 是否可以将 USB0_VBUS 检测引脚悬空？
在 AM335x 原理图检查清单 (SPRABN2A) 中：
USB 外设的典型连接： USBx_VBUS 应直接连接到 USB 连接器上的 VBUS 引脚
USB 主机的典型连接：USBx_VBUS 应连接到 5V VBUS 电源的输出端
准则规定“应“而不是“必须“。 USB0_VBUS 导致的 OC 是否未检测到任何电压？ 如果是、我们如何在不连接 USB0_VBUS 的情况下启动 USB0？
以下是 lsusb -v 和 dmesg 的输出
[ 80.764720] usb usb1-port1: over-current condition
[ 80.905195] musb-hdrc musb-hdrc.0: VBUS_ERROR in a_wait_vrise (81, <SessEnd), retry #1, port1 0000010c
[ 81.057622] musb-hdrc musb-hdrc.0: VBUS_ERROR in a_wait_vrise (81, <SessEnd), retry #2, port1 0000010c
[ 81.210062] musb-hdrc musb-hdrc.0: VBUS_ERROR in a_wait_vrise (81, <SessEnd), retry #3, port1 0000010c
[ 81.362484] musb-hdrc musb-hdrc.0: VBUS_ERROR in a_wait_vrise (80, <SessEnd), retry #3, port1 0008010clsusb -v
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 2.00
bDeviceClass 9 Hub
bDeviceSubClass 0
bDeviceProtocol 1 Single TT
bMaxPacketSize0 64
idVendor 0x1d6b Linux Foundation
idProduct 0x0002 2.0 root hub
bcdDevice 6.01
iManufacturer 3 Linux 6.1.46 musb-hcd
iProduct 2 MUSB HDRC host driver
iSerial 1 musb-hdrc.0
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 0x0019
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 0
bmAttributes 0xe0
Self Powered
Remote Wakeup
MaxPower 0mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 9 Hub
bInterfaceSubClass 0
bInterfaceProtocol 0 Full speed (or root) hub
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0004 1x 4 bytes
bInterval 12
Hub Descriptor:
bLength 9
bDescriptorType 41
nNbrPorts 1
wHubCharacteristic 0x0011
Per-port power switching
No overcurrent protection
TT think time 8 FS bits
bPwrOn2PwrGood 5 * 2 milli seconds
bHubContrCurrent 0 milli Ampere
DeviceRemovable 0x02
PortPwrCtrlMask 0xff
Hub Port Status:
Port 1: 0000.010c power oc suspend
Device Status: 0x0001
Self Powered