/dev/ttyACM* missing after reboot

[fabio_poiatti]

Hi

I was working without any problem with a MODEM connected via /dev/ttyACM* to my IMX6ULL in aour custom board.

I executed a reboot on the processor without switch off (both MODEM and IMX6ULL)

the /dev/ttyACM* didn't coming up :-(

Any suggestion?

Thanks

Fabio

[fabio_poiatti]

thanks Igor ... but it is not so easy to make a reset to external modem ..

in working condition I see the 6 virtual port on /dev/ttyACM* associated to USB port seen 

with lsusb command

Bus 001 Device 004: ID 1546:1102 U-Blox AG

in not working condition this USB port is not present

I tried a restart of udev but withou success

Do you have a suggestion to restart the USB service?

thanks

Fabio

[fabio_poiatti]

After some analysis, I see with normal working ... power on

lsusb

Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

Bus 001 Device 003: ID 1546:1102 U-Blox AG

Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

ls /sys/bus/usb/drivers

asix cdc_ether pegasus usbfs

ath3k cdc_ncm r8152 usbhid

ax88179_178a cdc_subset rtl8150 zaurus

bcm203x hub usb

btusb kaweth usb-storage

cdc_acm net1080 usb_ehset_test

ls /sys/bus/usb/drivers/cdc_acm

1-1:1.0 1-1:1.11 1-1:1.2 1-1:1.5 1-1:1.8 module uevent

1-1:1.1 1-1:1.12 1-1:1.3 1-1:1.6 1-1:1.9 new_id unbind

1-1:1.10 1-1:1.13 1-1:1.4 1-1:1.7 bind remove_id

And with not working situation, the cdc_acm drivers is not up and then also 

Bus 001 Device 003: ID 1546:1102 U-Blox AG

does not come up ..

During the reboot actions, the log has this error:

usb 1-1: device no response, device descriptor read/64, error -71

but I'm not able to power down/off the modem connected to usb ...

Any suggestions?

Thanks

[igorpadykov]

one can try to disable usb module and its clocks, then reenable again.

Best regards
igor

[fabio_poiatti]

how is it possible by software?

[igorpadykov]

it is usb clock in CCM_CCGR6 register, usb registers described in
Table 56-34. Default Values of Operational Register Space

i.MX 6ULL Applications Processor Reference Manual

[fabio_poiatti]

thanks,

resolved via modem hardware reset

[igorpadykov]

Hi Fabio

rebooting board without short removing board power may leave some modules

in non-reset state. So reinitialization after reboot will not correctly configure them.

In general one can try to compare usb registers in working and not working (after reboot) case

and perform additional resets (if possible) for external devices like modems.

Best regards
igor
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