btattach

Is not working in 3wire aka H:5 mode.

# strace btattach -B /dev/ttymxc1 -S 1000000 -P 3wire

...
write(1, "Attaching Primary controller to "..., 45Attaching Primary controller to /dev/ttymxc1) = 45
openat(AT_FDCWD, "/dev/ttymxc1", O_RDWR|O_NOCTTY) = 4
ioctl(4, TCFLSH, TCIOFLUSH)             = 0
ioctl(4, TIOCGETD, [0])                 = 0
ioctl(4, SNDCTL_TMR_START or TCSETS, {c_iflag=, c_oflag=NL0|CR0|TAB0|BS0|VT0|FF0|, c_cflag=B1000000|CS8|CREAD|CLOCAL|CRTSCTS, c_lflag=, ...}) = 0
ioctl(4, TIOCSETD, [15])                = 0
write(1, "Switched line discipline from 0 "..., 38Switched line discipline from 0 to 15) = 38
ioctl(4, _IOC(_IOC_WRITE, 0x55, 0xcb, 0x4), 0x2) = 0
ioctl(4, _IOC(_IOC_WRITE, 0x55, 0xc8, 0x4), 0x2) = 0
ioctl(4, _IOC(_IOC_READ, 0x55, 0xca, 0x4), 0x2) = -1 EUNATCH (Protocol driver not attached)
...
write(5, "Failed to get device id: Protoco"..., 54Failed to get device id: Protocol driver not attached) = 54
...
write(2, "No controller attached\n", 23No controller attached) = 23

strace hciattach -n /dev/ttymxc1 3wire 1000000 flow

• -n Don't detach from controlling terminal.