按照ST的官方readme移植HAL后开机一直卡在android界面，看logcat提示写文件时errorcode：-13。查下资料大致明白13错误码是权限不足，浏览代码在写文件的接口加日志后，发现是需要写iio:device*/buffer/enable这类文件的时候报错的。千万不要傻傻的手动去修改这一个文件的权限（我就是那个傻子），修改完编译好刷机后，你会发现又有别的文件没权限依旧报-13,。而且，每次开机手动加权限实在太恶心。仔细看文档后，发现还有个文件：
/hardware/STMicroelectronics/SensorHAL_IIO/Documentation/ueventd.example.rc
这个文件里面给出了需要加权限的文件路径，如下图：
理论上是把这个文件的内容拷贝到如下路径文件添加到末尾就行：
/device/rockchip/common/rootdir/ueventd.rockchip.rc
但是系统原因，iio:device所在路径可能有变化，我的路径在：/sys/bus/iio/devices/iio:device，与文档就不一致。所以要根据自身系统情况修改前缀。
除了文档列出的，还有一个路径需要加：/sys/bus/iio/devices/iio:device* current_timestamp_clock 0666 system system
增加内容：
#common iio char devices
/dev/iio:device* 0666 system system
/sys/bus/iio/devices/iio:device* current_timestamp_clock 0666 system system
#common sensors files
/sys/bus/iio/devices/iio:device* buffer/enable 0666 system system
/sys/bus/iio/devices/iio:device* buffer/length 0666 system system
/sys/bus/iio/devices/iio:device* sampling_frequency 0666 system system
/sys/bus/iio/devices/iio:device* scan_elements/in_timestamp_en 0666 system system
/sys/bus/iio/devices/iio:device* hwfifo_flush 0666 system system
/sys/bus/iio/devices/iio:device* hwfifo_enabled 0666 system system
/sys/bus/iio/devices/iio:device* hwfifo_watermark 0666 system system
/sys/bus/iio/devices/iio:device* injection_mode 0666 system system
#accelerometer sensor
/sys/bus/iio/devices/iio:device* scan_elements/in_accel_x_en 0666 system system
/sys/bus/iio/devices/iio:device* scan_elements/in_accel_y_en 0666 system system
/sys/bus/iio/devices/iio:device* scan_elements/in_accel_z_en 0666 system system
/sys/bus/iio/devices/iio:device* in_accel_x_scale 0666 system system
/sys/bus/iio/devices/iio:device* in_accel_y_scale 0666 system system
/sys/bus/iio/devices/iio:device* in_accel_z_scale 0666 system system
/sys/bus/iio/devices/iio:device* in_accel_injection_raw 0666 system system
#magnetometer sensor
/sys/bus/iio/devices/iio:device* scan_elements/in_magn_x_en 0666 system system
/sys/bus/iio/devices/iio:device* scan_elements/in_magn_y_en 0666 system system
/sys/bus/iio/devices/iio:device* scan_elements/in_magn_z_en 0666 system system
/sys/bus/iio/devices/iio:device* in_magn_x_scale 0666 system system
/sys/bus/iio/devices/iio:device* in_magn_y_scale 0666 system system
/sys/bus/iio/devices/iio:device* in_magn_z_scale 0666 system system
#gyroscope sensor
/sys/bus/iio/devices/iio:device* scan_elements/in_anglvel_x_en 0666 system system
/sys/bus/iio/devices/iio:device* scan_elements/in_anglvel_y_en 0666 system system
/sys/bus/iio/devices/iio:device* scan_elements/in_anglvel_z_en 0666 system system
/sys/bus/iio/devices/iio:device* in_anglvel_x_scale 0666 system system
/sys/bus/iio/devices/iio:device* in_anglvel_y_scale 0666 system system
/sys/bus/iio/devices/iio:device* in_anglvel_z_scale 0666 system system
#pressure sensor
/sys/bus/iio/devices/iio:device* scan_elements/in_pressure_en 0666 system system
/sys/bus/iio/devices/iio:device* scan_elements/in_temp_en 0666 system system
/sys/bus/iio/devices/iio:device* in_pressure_scale 0666 system system
#step counter sensor
/sys/bus/iio/devices/iio:device* max_delivery_rate 0666 system system
/sys/bus/iio/devices/iio:device* reset_counter 0666 system system
/sys/bus/iio/devices/iio:device* scan_elements/in_step_counter_en 0666 system system
#significant motion sensor
/sys/bus/iio/devices/iio:device* scan_elements/in_sign_motion_en 0666 system system
#step detector sensor
/sys/bus/iio/devices/iio:device* scan_elements/in_step_detector_en 0666 system system
#tilt sensor
/sys/bus/iio/devices/iio:device* scan_elements/in_tilt_en 0666 system system
添加好后，还有个坑，文件前面可能有同路径的配置，可能会有影响，需要自己排查处理。
修改好后，就可以实现开机顺利启动不需要手动添加权限了。
新人入行，经验分享，如有所误，欢迎指出~
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