ttyo4 not working on BBB rev. C


I’m using kernel 3.8.13-bone67 on BeagleBone Black,

I have a problem with serial port ttyO4 …loopback doesn’t works !

The other serial port works but not ttyO4 (Rx works but not Tx !)

Same problem with 3.8.13-bone40 and also with another same board …

board-name A335BNLT
revision 00C0
serial-number 2814BBBK4931

My uenv.txt : optargs=capemgr.disable_partno=BB-BONELT-HDMI,BB-BONELT-HDMIN capemgr.enable_partno=BB-UART1,BB-UART2,BB-UART2-RTSCTS,BB-UART4,BB-UART4-RTSCTS,BB-ADC

Do you have an idea ?