问题：

频繁插拔tf卡，需要插拔usb数据线或者输入otg主从切换命令。

解决方法：

1 修改/etc/udev/rules.d/automount.rules

# Media automounting

SUBSYSTEM=="block", ACTION=="add"    RUN+="/etc/udev/scripts/mount.sh"

SUBSYSTEM=="block", ACTION=="remove" RUN+="/etc/udev/scripts/mount.sh"

SUBSYSTEM=="block", ACTION=="change", ENV{DISK_MEDIA_CHANGE}=="1" RUN+="/etc/udev/scripts/mount.sh"

SUBSYSTEM=="block", KERNEL=="mmcblk1", ACTION=="add"    RUN+="/etc/udev/scripts/1.sh"

SUBSYSTEM=="block", KERNEL=="mmcblk1", ACTION=="remove" RUN+="/etc/udev/scripts/2.sh"

2 添加/etc/udev/scripts/1.sh

#!/bin/bash

modprobe g_mass_storage file=/dev/mmcblk1 luns=1 stall=0 removable=1 &

echo host > /sys/devices/platform/fe8a0000.usb2-phy/otg_mode &

echo peripheral > /sys/devices/platform/fe8a0000.usb2-phy/otg_mode &

3 添加/etc/udev/scripts/2.sh

#!/bin/bash

rmmod g_mass_storage

4 执行chmod +x /etc/udev/scripts/1.sh

chmod +x /etc/udev/scripts/2.sh

5 插入TF卡电脑端会自动显示盘符，弹出TF卡需要先在电脑端弹出，再拔出TF卡。