On Wed, 2020-05-20 at 08:08 -0500, Dan Williams wrote:
> On Wed, 2020-05-20 at 12:43 +0000, Joakim Tjernlund wrote:
> > On Tue, 2020-05-19 at 14:54 +0200, Greg KH wrote:
> > > CAUTION: This email originated from outside of the organization. Do
> > > not click links or open attachments unless you recognize the sender
> > > and know the content is safe.
> > >
> > >
> > > On Tue, May 19, 2020 at 12:14:55PM +0000, Joakim Tjernlund wrote:
> > > > Whenever we connect a Linux laptop(4.19.118) to our ttyACM serial
> > > > gadget we can see som strange
> > > > chars appearing in our gadget:
> > > > 03�`3�03�x�x(in hex: 3033 efbf bd60 33ef bfbd 3033 efbf bd78 efbf
> > > > bd78)
> > > > They appear witch c.a 1 sec in between.
> > > > I assume it is the laptops ACM driver emitting those, but why?
> > > > Can these chars be turned off?
> > >
> > > It's a program on your laptop probing the device. Usually
> > > modemmanager
> > > or something like that.
> > >
> > > greg k-h
> >
> > Right you were, it was modemmanager :)
>
> If the device has a unique ID that isn't a modem, it can be added to
> ModemManager's blacklist.
Yes, I did that:
cat /etc/udev/rules.d/70-mm-usb-LC-blacklist.rules
ACTION!="add|change|move|bind", GOTO="mm_usb_device_blacklist_end"
SUBSYSTEM!="usb", GOTO="mm_usb_device_blacklist_end"
# XTM LC serial port
ATTRS{idVendor}=="0424", ATTRS{idProduct}=="274e", ENV{ID_MM_TTY_BLACKLIST}="1"
LABEL="mm_usb_device_blacklist_end"
>
> Also note that recent versions of ModemManager flipped the logic and
> will only probe *known* modems, require explicit requests to probe
> possible modems, and of course won't probe anything on the blacklist.
I got 1.12.6, not new enough I guess?
>
> Dan
>
> > Fixing that I can occasion se in my DE:
> > [Wed May 20 14:03:16 2020] cdc_ether 1-6.2:1.0 usb0: unregister
> > 'cdc_ether' usb-0000:00:14.0-6.2, CDC Ethernet Device
> > [Wed May 20 14:03:25 2020] usb usb1-port6: disabled by hub (EMI?),
> > re-enabling...
> > [Wed May 20 14:03:25 2020] usb 1-6: USB disconnect, device number 85
> > [Wed May 20 14:03:25 2020] cdc_acm 1-6.3:1.1: acm_ctrl_irq -
> > usb_submit_urb failed: -19
> > [Wed May 20 14:03:25 2020] usb 1-6-port2: attempt power cycle
> > [Wed May 20 14:03:26 2020] usb 1-6.3: USB disconnect, device number
> > 86
> > [Wed May 20 14:03:26 2020] cdc_acm 1-6.3:1.1: failed to set dtr/rts
> > [Wed May 20 14:03:26 2020] usb 1-6: new high-speed USB device number
> > 94 using xhci_hcd
> > [Wed May 20 14:03:27 2020] hub 1-6:1.0: USB hub found
> > [Wed May 20 14:03:27 2020] hub 1-6:1.0: 3 ports detected
> > [Wed May 20 14:03:27 2020] usb 1-6.2: new high-speed USB device
> > number 95 using xhci_hcd
> > [Wed May 20 14:03:27 2020] cdc_ether 1-6.2:1.0 usb0: register
> > 'cdc_ether' at usb-0000:00:14.0-6.2, CDC Ethernet Device,
> > 7e:1d:06:c0:3f:3c
> > [Wed May 20 14:03:27 2020] usb 1-6.3: new high-speed USB device
> > number 96 using xhci_hcd
> > [Wed May 20 14:03:27 2020] cdc_acm 1-6.3:1.1: ttyACM0: USB ACM device
> >
> > This "disabled by hub (EMI?), re-enabling" may be from:
> > EM interference sometimes causes bad shielded USB devices to
> > be shutdown by the hub, this hack enables them again.
> >
> > But a another side effect from this is that I get a lot of garbage
> > chars in the other end, like:
> > h�^@^@� ^@^@� ^@
> > or
> > X���)H��4Ğ^���
> > I wonder if this can be caused by the USB/ACM driver ?
> >
> > Jocke
