We had buy another two AR750S modules, but the gpio pin 22 still has the same problem (The gpio 22 can not be set to LOW).
The first one testing record (MAC=E4:95:6E:45:A0:D8)
root@GL-AR750S:~# ifconfig eth0
eth0 Link encap:Ethernet HWaddr E4:95:6E:45:A0:D8
inet6 addr: fe80::e695:6eff:fe45:a0d8/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1115326 errors:0 dropped:0 overruns:0 frame:0
TX packets:942661 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:219084931 (208.9 MiB) TX bytes:177970230 (169.7 MiB)
Interrupt:4
root@GL-AR750S:~# echo 0 > /sys/class/gpio/gpio22/value
root@GL-AR750S:~# cat /sys/kernel/debug/gpio
gpiochip0: GPIOs 0-31, parent: platform/ath79-gpio, ath79-gpio:
gpio-1 ( |gl-ar750s:white:powe) out lo
gpio-2 ( |reset ) in hi
gpio-5 ( |sda ) in hi
gpio-7 ( |gl-ar750s:white:usbp) out hi
gpio-8 ( |right ) in hi
gpio-18 ( |sysfs ) out lo
gpio-19 ( |gl-ar750s:white:wlan) out lo
gpio-20 ( |gl-ar750s:white:wlan) out lo
gpio-21 ( |scl ) in hi
gpio-22 ( |sysfs ) out hi
gpiochip1: GPIOs 489-511, parent: platform/qca956x_wmac, ath9k-phy1:
gpio-490 ( |ath9k-phy1 ) in lo
The second one testing record (MAC=E4:95:6E:45:99:3A)
root@GL-AR750S:~# ifconfig eth0
eth0 Link encap:Ethernet HWaddr E4:95:6E:45:99:3A
inet6 addr: fe80::e695:6eff:fe45:993a/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1853 errors:0 dropped:0 overruns:0 frame:0
TX packets:1362 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:242653 (236.9 KiB) TX bytes:234321 (228.8 KiB)
Interrupt:4
root@GL-AR750S:~# echo 0 > /sys/class/gpio/gpio22/value
root@GL-AR750S:~# cat /sys/kernel/debug/gpio
gpiochip0: GPIOs 0-31, parent: platform/ath79-gpio, ath79-gpio:
gpio-1 ( |gl-ar750s:white:powe) out lo
gpio-2 ( |reset ) in hi
gpio-5 ( |sda ) in hi
gpio-7 ( |gl-ar750s:white:usbp) out hi
gpio-8 ( |right ) in hi
gpio-18 ( |sysfs ) out hi
gpio-19 ( |gl-ar750s:white:wlan) out lo
gpio-20 ( |gl-ar750s:white:wlan) out hi
gpio-21 ( |scl ) in hi
gpio-22 ( |sysfs ) out hi
gpiochip1: GPIOs 489-511, parent: platform/qca956x_wmac, ath9k-phy1:
gpio-490 ( |ath9k-phy1 ) in lo
However, the gpio 18 is correct in the testing.
Maybe it is cause by a hardware or a driver error?