TI中文支持网使用PROCESSOR-SDK-LINUX-AM335X 06_03_00_106的arago-base-tisdk-image-am335x-evm 作为根文件系统时，插入USB，系统无法读取信息。
但使用tisdk-rootfs-image-am335x-evm时，却能读取USB信息，且能正常使用，请问这是怎么回事
使用arago-base-tisdk-image-am335x-evm 时与usb相关log：
[ 22.573840] am335x-phy-driver 47401300.usb-phy: using lookup tables for GPIO lookup
[ 22.573849] am335x-phy-driver 47401300.usb-phy: No GPIO consumer reset found
[ 22.573858] am335x-phy-driver 47401300.usb-phy: GPIO lookup for consumer vbus-detect
[ 22.573864] am335x-phy-driver 47401300.usb-phy: using device tree for GPIO lookup
[ 22.573880] of_get_named_gpiod_flags: can't parse 'vbus-detect-gpios' property of node '/ocp/usb@47400000/usb-phy@47401300[0]'
[ 22.573894] of_get_named_gpiod_flags: can't parse 'vbus-detect-gpio' property of node '/ocp/usb@47400000/usb-phy@47401300[0]'
[ 22.573902] am335x-phy-driver 47401300.usb-phy: using lookup tables for GPIO lookup
[ 22.573909] am335x-phy-driver 47401300.usb-phy: No GPIO consumer vbus-detect found
[ 22.574034] am335x-phy-driver 47401300.usb-phy: 47401300.usb-phy supply vcc not found, using dummy regulator
[ 22.645629] input: ti-tsc as /devices/platform/ocp/44e0d000.tscadc/TI-am335x-tsc.0.auto/input/input0
[ 22.702837] am335x-phy-driver 47401300.usb-phy: Linked as a consumer to regulator.0
[ 23.108968] usbcore: registered new interface driver usbfs
[ 23.202916] usbcore: registered new interface driver hub
[ 23.261219] usbcore: registered new device driver usb
[ 23.630205] musb-hdrc musb-hdrc.0: MUSB HDRC host driver
[ 23.730783] musb-hdrc musb-hdrc.0: new USB bus registered, assigned bus number 1
[ 23.785430] usb usb1: New USB device found, idVendor=1d6b, idProduct=0002, bcdDevice= 4.19
[ 23.850832] usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1
[ 23.858133] usb usb1: Product: MUSB HDRC host driver
[ 23.955401] usb usb1: Manufacturer: Linux 4.19.94-gbe5389fd85 musb-hcd
[ 24.020327] usb usb1: SerialNumber: musb-hdrc.0
[ 24.055568] hub 1-0:1.0: USB hub found
Nancy Wang：
使用tisdk-rootfs-image-am335x-evm时,读取的信息可以贴出来看一下吗？
,
ZB_LAJI：
插入usb后，串口打印信息：root@am335x-evm:~# root@am335x-evm:~# [ 110.380651] usb 1-1: new high-speed USB device number 3 using musb-hdrc[ 110.565341] usb 1-1: New USB device found, idVendor=05e3, idProduct=0749, bcdDevice=15.35[ 110.573752] usb 1-1: New USB device strings: Mfr=3, Product=4, SerialNumber=2[ 110.584078] usb 1-1: Product: USB3.0 Card Reader[ 110.588760] usb 1-1: Manufacturer: Generic[ 110.595708] usb 1-1: SerialNumber: 000000001536[ 110.609836] usb-storage 1-1:1.0: USB Mass Storage device detected[ 110.631298] scsi host0: usb-storage 1-1:1.0[ 111.683025] scsi 0:0:0:0: Direct-Access Generic MassStorageClass 1536 PQ: 0 ANSI: 6[ 112.026921] sd 0:0:0:0: [sda] 62521344 512-byte logical blocks: (32.0 GB/29.8 GiB)[ 112.036489] sd 0:0:0:0: [sda] Write Protect is off[ 112.047287] sd 0:0:0:0: [sda] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA[ 112.070279] sda: sda1[ 112.086261] sd 0:0:0:0: [sda] Attached SCSI removable disk
root@am335x-evm:~#
启动时，相关log：[ 21.943007] am335x-phy-driver 47401300.usb-phy: GPIO lookup for consumer reset[ 21.943026] am335x-phy-driver 47401300.usb-phy: using device tree for GPIO lookup[ 21.943062] of_get_named_gpiod_flags: can't parse 'reset-gpios' property of node '/ocp/usb@47400000/usb-phy@47401300[0]'[ 21.943080] of_get_named_gpiod_flags: can't parse 'reset-gpio' property of node '/ocp/usb@47400000/usb-phy@47401300[0]'[ 21.943091] am335x-phy-driver 47401300.usb-phy: using lookup tables for GPIO lookup[ 21.943099] am335x-phy-driver 47401300.usb-phy: No GPIO consumer reset found[ 21.943108] am335x-phy-driver 47401300.usb-phy: GPIO lookup for consumer vbus-detect[ 21.943114] am335x-phy-driver 47401300.usb-phy: using device tree for GPIO lookup[ 21.943130] of_get_named_gpiod_flags: can't parse 'vbus-detect-gpios' property of node '/ocp/usb@47400000/usb-phy@47401300[0]'[ 21.943145] of_get_named_gpiod_flags: can't parse 'vbus-detect-gpio' property of node '/ocp/usb@47400000/usb-phy@47401300[0]'[ 21.943152] am335x-phy-driver 47401300.usb-phy: using lookup tables for GPIO lookup[ 21.943159] am335x-phy-driver 47401300.usb-phy: No GPIO consumer vbus-detect found[ 21.943284] am335x-phy-driver 47401300.usb-phy: 47401300.usb-phy supply vcc not found, using dummy regulator[ 22.076190] am335x-phy-driver 47401300.usb-phy: Linked as a consumer to regulator.0[ 22.178240] musb-hdrc musb-hdrc.0: MUSB HDRC host driver[ 22.264409] musb-hdrc musb-hdrc.0: new USB bus registered, assigned bus number 1[ 22.384087] usb usb1: New USB device found, idVendor=1d6b, idProduct=0002, bcdDevice= 4.19[ 22.472593] usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1[ 22.541977] usb usb1: Product: MUSB HDRC host driver[ 22.589992] usb usb1: Manufacturer: Linux 4.19.94-gbe5389fd85 musb-hcd[ 22.665110] usb usb1: SerialNumber: musb-hdrc.0[ 22.713177] hub 1-0:1.0: USB hub found
,
Nancy Wang：
我咨询一下相关工程师，再给你回复。
,
Nancy Wang：
抱歉再确认一下，在两个文件系统下usb都是能正常工作的吗？
您想咨询的是不通文件系统下终端输出调试信息的不同吗？
,
ZB_LAJI：
不对，
使用arago-base-tisdk-image-am335x-evm 根文件系统是usb未正常工作，无插拔信息提示，也不能读取数据。
使用tisdk-rootfs-image-am335x-evm才能使用正常使用
,
Nancy Wang：
AM335x USB端口是host还是OTG模式？该模式由内核设备树中的dr_mode属性定义。
如果处于“ otg”模式，请在两种情况下分别提供以下命令的输出。
root@am335x-evm:~# cat /sys/class/udc/musb-hdrc.0/uevent
,
ZB_LAJI：
检查了一下，发现设备树中的 dr_mode 没有定义，现在添加dr_mode 为 host。
添加后，均可识别USB，并成功读写数据。
但插入USB后串口信息中“”Write cache: disabled, read cache: enabled, doesn't support DPO or FUA“”是什么意思？是否会影响使用？
[ 78.335004] usb 1-1: New USB device found, idVendor=05e3, idProduct=0749, bcdDevice=15.35[ 78.343361] usb 1-1: New USB device strings: Mfr=3, Product=4, SerialNumber=2[ 78.353520] usb 1-1: Product: USB3.0 Card Reader[ 78.358198] usb 1-1: Manufacturer: Generic[ 78.365121] usb 1-1: SerialNumber: 000000001536[ 78.432026] usb-storage 1-1:1.0: USB Mass Storage device detected[ 78.446284] scsi host0: usb-storage 1-1:1.0[ 78.457608] usbcore: registered new interface driver usb-storage[ 78.476455] usbcore: registered new interface driver uas[ 79.522842] scsi 0:0:0:0: Direct-Access Generic MassStorageClass 1536 PQ: 0 ANSI: 6[ 79.835726] sd 0:0:0:0: [sda] 62333952 512-byte logical blocks: (31.9 GB/29.7 GiB)[ 79.844950] sd 0:0:0:0: [sda] Write Protect is off[ 79.861614] sd 0:0:0:0: [sda] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA[ 79.885551] sda: sda1[ 79.898068] sd 0:0:0:0: [sda] Attached SCSI removable disk
,
Nancy Wang：
这表示禁用了写缓存，这是为了最大程度地减少系统电源故障中的数据丢失。
DPO和FUA是SCSI参数，通常不适用于USB thumb drives。
