[SOLVED] USB-to-Serial adapter not shown in /dev anymore

slacksam · 09-16-2016, 03:24 AM

On my RPi1 when Slackware ARM 14.1 and kernel 3.18.8 was installed, my USB-to-LAN adapter used to appear as /dev/ttyUSB0. But now, with Slackware ARM 14.2 and kernel 4.4.20, when I plug in the adapter, no /dev/ttyUSB* is being shown anymore.

Any ideas how to fix that?

Could that behavior be related to the problem I described in my last tread?

ferrari · 09-16-2016, 04:24 AM

I would expect a USB-to-LAN device to associated with a network device node (as opposed to a /dev/ttyUSB* device node).

Check with

Code:

/sbin/ifconfig -a

If nothing, check kernel module loaded (if any) for the device concerned

Code:

/sbin/lspci -nnk

slacksam · 09-16-2016, 05:17 AM

@ferrari:
Thanks for your reply, but sorry, I made a mistake. It's not an USB-to-LAN adapter but an USB-to-Serial adapter. My bad.(Now I changed the thread title from USB-to-LAN to USB-to-Serial)

Doing a

Code:

/sbin/lspci -nnk

shows

Code:

pcilib: Cannot open /proc/bus/pci
lspci: Cannot find any working access method.

Now I made a downgrade to kernel 3.18.8 and it's being shown as /dev/ttyUSB0 again.

drmozes · 09-16-2016, 07:48 AM

Do

Code:

lsmod | sort > /tmp/lsmod-3.18

Boot back into the 4.x kernel and run lsmod again and compare the differences - there will probably be a few differences module name may be obvious which is the one handling your device.
The chances are that the 4.x kernel was updated and some how the module has become de-selected, or maybe the module was abandoned and is no longer present in Linux.

slacksam · 09-16-2016, 09:13 AM

@drmozes:
Thanks for your advice.
Here's the result:

Code:

~# diff -u lsmod-3.18.8 lsmod-4.4.20                                                         
--- lsmod-3.18.8        2016-09-16 16:09:05.795193000 +0200
+++ lsmod-4.4.20        2016-09-16 16:12:04.254979000 +0200
@@ -1,12 +1 @@
 Module                  Size  Used by
-bcm2708_dmaengine       7505  0
-evdev                   9944  0
-fuse                   83009  1
-ipv6                  326818  10
-led_class               4070  1 leds_gpio
-leds_gpio               3507  0
-pl2303                  8650  0
-uio                     8660  1 uio_pdrv_genirq
-uio_pdrv_genirq         3202  0
-usbserial              27436  1 pl2303
-virt_dma                2313  1 bcm2708_dmaengine

[edit] The output of lsmod with kernel 4.4.20 is empty, so no modules are loaded.

drmozes · 09-16-2016, 09:39 AM

Quote:

Originally Posted by slacksam

The output of lsmod with kernel 4.4.20 is empty, so no modules are loaded.

Yes so that's your problem as it is in the other thread.
Are you sure that the Kernel modules package is installed?
Are there any modules at all in /lib/modules/4.xxx ?

slacksam · 09-16-2016, 09:52 AM

Code:

~$ ls /var/log/packages/kernel-modules-*
/var/log/packages/kernel-modules-raspi-3.18.8-arm-1_02Mar15_fd
/var/log/packages/kernel-modules-sarpi-4.4.20-arm-1_slack14.2_fd0

I attached the output for

Code:

tree /lib/modules/4.4.20-arm/

in a text file:

drmozes · 09-16-2016, 10:17 AM

Quote:

Originally Posted by slacksam

Code:

~$ ls /var/log/packages/kernel-modules-*
/var/log/packages/kernel-modules-raspi-3.18.8-arm-1_02Mar15_fd
/var/log/packages/kernel-modules-sarpi-4.4.20-arm-1_slack14.2_fd0

I attached the output for

Code:

tree /lib/modules/4.4.20-arm/

in a text file:

So the modules are there.

Did you upgrade 14.1 to 14.2 or do a fresh installation? There was no upgrade path (unless you looked at the x86 version and figured it out) for 14.1 to 14.2, so I wonder if something broke along the way.

Can you try doing

Code:

modprobe usbserial

If that does not work, try

Code:

insmod /lib/modules/4.4.20-arm/< path to the usbserial module>

Emerson · 09-16-2016, 10:58 AM

Try running depmod.

slacksam · 09-16-2016, 01:15 PM

Quote:

Originally Posted by drmozes

Did you upgrade 14.1 to 14.2 or do a fresh installation? There was no upgrade path (unless you looked at the x86 version and figured it out) for 14.1 to 14.2, so I wonder if something broke along the way.

I did both. First I did an upgrade from 14.1 to 14.2 without kernel upgrade and all worked fine. Then I did a kernel upgrade which broke the system (which I described in the other tread). Then I did an fresh install without LVM on another sd card (which is the installation I'm using in this thread).

Ok, now i see what's wrong:

Code:

~# modprobe usbserial
modprobe: FATAL: Module usbserial not found in directory /lib/modules/4.4.20+

Code:

~# depmod
depmod: ERROR: could not open directory /lib/modules/4.4.20+: No such file or directory
depmod: FATAL: could not search modules: No such file or directory

Code:

~# ls /var/log/packages/kernel*
/var/log/packages/kernel-firmware-20160628git-noarch-1
/var/log/packages/kernel-headers-4.4.14-arm-1
/var/log/packages/kernel-modules-raspi-3.18.8-arm-1_02Mar15_fd
/var/log/packages/kernel-modules-sarpi-4.4.20-arm-1_slack14.2_fd0
/var/log/packages/kernel_raspi-3.18.8-arm-1_02Mar15_fd
/var/log/packages/kernel_sarpi-4.4.20-arm-1_slack14.2_fd0

Loading the module with

Code:

~# insmod /lib/modules/4.4.20-arm/kernel/drivers/usb/serial/usbserial.ko

worked without an error.

Code:

~# uname -r
4.4.20+

Looks like a bug in the kernel config.
The packages were from http://rpi.fatdog.eu/index.php?p=rpi1get142.

[edit] For now I fixed it by doing

Code:

~# cd /lib/modules/
~# ln -s 4.4.20-arm `uname -r`

Exaga · 09-20-2016, 02:45 AM

Quote:

Originally Posted by slacksam

Looks like a bug in the kernel config.
The packages were from http://rpi.fatdog.eu/index.php?p=rpi1get142.

[edit] For now I fixed it by doing

Code:

~# cd /lib/modules/
~# ln -s 4.4.20-arm `uname -r`

New installer image and packages for the RPi 1. Tested and double-tested. Modules are being loaded correctly and everything else seems to be working as expected. Using kernel 4.4.21 with the latest RPi boot firmware.

http://sarpi.fatdog.eu/index.php?p=rpi1get142

Let me know if you find any more problems.

slacksam · 09-20-2016, 08:25 AM

@Exaga: Works. Thanks!