通过sysfs启用Flash和Torch LEDs:
1. Echo a nonzero number into the brightness node to configure the current.
2. Echo 1 into the switch’s regulator node to enable the Flash regulator (BoB).
3. Echo 1 into the switch’s brightness node.
切换节点有两个:
1. Switch_0 for LED0/1
2. Switch_1 for LED2
每次重新触发Flash/Torch时，必须重置当前值。（重启一下便可）
运行以下命令来测试每个flash:
adb shell "echo 1000 > /sys/class/leds/led:flash_0/brightness"
adb shell "echo 1 > /sys/class/leds/led:switch_0/brightness"
运行以下命令来启用两个前端flash:
adb shell "echo 500 > /sys/class/leds/led:flash_0/brightness"
adb shell "echo 500 > /sys/class/leds/led:flash_1/brightness"
adb shell "echo 1 > /sys/class/leds/led:switch_0/brightness"
运行以下命令来禁用两个前端flash:
adb shell "echo 0 > /sys/class/leds/led:switch_0/brightness"
运行以下命令打开torch:
adb shell "echo 100 > /sys/class/leds/led:torch_0/brightness"
adb shell "echo 100 > /sys/class/leds/led:torch_1/brightness"
adb shell "echo 1 > /sys/class/leds/led:switch_0/brightness"
led:switch node:开关节点可以同时打开或关闭多个led。为了简化操作，LED开关节点从其他节点获得多个现有属性。LED开关节点是可选的，以保持向后兼容性。
相关文件:
kernel/drivers/leds/leds-qpnp-flash-v2.