tca9535的a0,a1,a2全是高电平，没有rst引脚。接到i2c3-M1上。
&i2c3 {
status = "okay";
clock-frequency = <100000>;
pinctrl-names = "default";
pinctrl-0 = <&i2c3m1_xfer>;

tca9535@4e {
compatible = "nxp,pca9535";
reg = <0x4e>; //之前用i2cdetect -y 3 检测是27，但总不行，所以尝试用4e
#address-cells = <1>;
#size-cells = <0>;
gpio ...