I followed this guide and enabled a serial console over USB. I can connect and log in from Windows but my Ubuntu laptop can't access the serial console.
The Raspberry shows up ad a tty device in /dev/ttyACM0 but when I connect to it I get nothing. dmesg shows a "failed to set dtr/rts" message every time I try to access the tty:
[ 3851.710852] usb 1-8: USB disconnect, device number 7
[ 3875.185832] usb 1-3: new high-speed USB device number 8 using xhci_hcd
[ 3880.921852] usb 1-3: device descriptor read/64, error -110
[ 3881.178907] usb 1-3: New USB device found, idVendor=0525, idProduct=a4a7
[ 3881.178913] usb 1-3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 3881.178917] usb 1-3: Product: Gadget Serial v2.4
[ 3881.178921] usb 1-3: Manufacturer: Linux 4.14.79+ with 20980000.usb
[ 3881.179990] cdc_acm 1-3:2.0: ttyACM0: USB ACM device
[ 3897.226350] cdc_acm 1-3:2.0: failed to set dtr/rts
[ 3902.346458] cdc_acm 1-3:2.0: failed to set dtr/rts
[ 3919.242818] cdc_acm 1-3:2.0: failed to set dtr/rts
The command udevadm info -a -n /dev/ttyACM0 gives this information:
looking at device '/devices/pci0000:00/0000:00:14.0/usb1/1-3/1-3:2.0/tty/ttyACM0':
KERNEL=="ttyACM0"
SUBSYSTEM=="tty"
DRIVER==""
looking at parent device '/devices/pci0000:00/0000:00:14.0/usb1/1-3/1-3:2.0':
KERNELS=="1-3:2.0"
SUBSYSTEMS=="usb"
DRIVERS=="cdc_acm"
ATTRS{authorized}=="1"
ATTRS{bAlternateSetting}==" 0"
ATTRS{bInterfaceClass}=="02"
ATTRS{bInterfaceNumber}=="00"
ATTRS{bInterfaceProtocol}=="01"
ATTRS{bInterfaceSubClass}=="02"
ATTRS{bNumEndpoints}=="01"
ATTRS{bmCapabilities}=="2"
ATTRS{iad_bFirstInterface}=="00"
ATTRS{iad_bFunctionClass}=="02"
ATTRS{iad_bFunctionProtocol}=="01"
ATTRS{iad_bFunctionSubClass}=="02"
ATTRS{iad_bInterfaceCount}=="02"
ATTRS{interface}=="CDC Abstract Control Model (ACM)"
ATTRS{supports_autosuspend}=="1"
looking at parent device '/devices/pci0000:00/0000:00:14.0/usb1/1-3':
KERNELS=="1-3"
SUBSYSTEMS=="usb"
DRIVERS=="usb"
ATTRS{authorized}=="1"
ATTRS{avoid_reset_quirk}=="0"
ATTRS{bConfigurationValue}=="2"
ATTRS{bDeviceClass}=="02"
ATTRS{bDeviceProtocol}=="00"
ATTRS{bDeviceSubClass}=="00"
ATTRS{bMaxPacketSize0}=="64"
ATTRS{bMaxPower}=="2mA"
ATTRS{bNumConfigurations}=="1"
ATTRS{bNumInterfaces}==" 2"
ATTRS{bcdDevice}=="0414"
ATTRS{bmAttributes}=="c0"
ATTRS{busnum}=="1"
ATTRS{configuration}=="CDC ACM config"
ATTRS{devnum}=="8"
ATTRS{devpath}=="3"
ATTRS{idProduct}=="a4a7"
ATTRS{idVendor}=="0525"
ATTRS{ltm_capable}=="no"
ATTRS{manufacturer}=="Linux 4.14.79+ with 20980000.usb"
ATTRS{maxchild}=="0"
ATTRS{product}=="Gadget Serial v2.4"
ATTRS{quirks}=="0x0"
ATTRS{removable}=="removable"
ATTRS{speed}=="480"
ATTRS{urbnum}=="140"
ATTRS{version}==" 2.00"
Any idea on how I can troubleshoot this further?