How to Find and reload specific driver from kernel?

Question

I am using Crunchbang 64 bit O.S. with a ASUS N150 wireless adapter. Every time I close my laptop and it enters sleep mode, when I "wake it up" I am unable to connect back using the wireless adapter; I have to restart.

My questions are:

1. Is there a way to find the specific driver name? I know it's an ASUS N150 adapter with a Realtek chipset.

2. How can I reload the driver for the adapter without resetting the system?

3. How can I find my current kernel version via terminal (sidenote)?

Solution 1

way to find the specific driver name

• lspci | grep -i network

I am not sure whether that device is on the PCI or USB bus but you can try the following.

1. Use lsusb or lspci to find information about the device
2. Lookup that device for the corresponding module ("driver")
3. Make sure that module is loaded and available with lsmod and modprobe

Another Idea would be to use lsmod and diff to find out which modules are going missing when your laptop uses sleep mode. It could be more than one module that has a problem.

1. restart machine
2. make sure that the wifi adapter is working

3. use lsmod to get all loaded modules

   lsmod > loaded-modules-before-sleep.txt
   

4. put computer to sleep mode

5. wake machine up
6. make sure that the wifi adapter ISN'T working

7. use lsmod to get all loaded modules

   lsmod > loaded-modules-after-sleep.txt
   

8. use diff to see what has changed!

   diff loaded-modules-before-sleep.txt loaded-modules-after-sleep.txt
   

reload driver without resetting system

Once you know the module to load, simply use modprobe as root

• modprobe wifi_module_name

find current kernel version via terminal

uname to the rescue! uname should tell you what you want to know.

• uname -a

Solution 2

Adding a shorter and more specific answer for my own convenience :)

To find out the kernel module, issue lspci -vvnn | grep -A 9 Network (from ubuntu WifiDocs):

~$ lspci -vvnn | grep -A 9 Network 
03:00.0 Network controller [0280]: Broadcom Corporation BCM4331 802.11a/b/g/n [14e4:4331] (rev 02)
    Subsystem: Apple Inc. AirPort Extreme [106b:010f]
    Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
    Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
    Latency: 0, Cache Line Size: 256 bytes
    Interrupt: pin A routed to IRQ 17
    Region 0: Memory at a0500000 (64-bit, non-prefetchable) [size=16K]
    Capabilities: <access denied>
    Kernel driver in use: wl
    Kernel modules: bcma, wl

From this you can see that wl is in use.

To reload on demand, do

sudo rmmod wl && sudo modprobe wl

To reload on sleep/hibernate, install pm-utils and add a file with any name in /etc/pm/config.d/, for instance /etc/pm/config.d/suspend with the following contents:

SUSPEND_MODULES="wl"

This is explained at Arch pm-utils wiki and pm-action man page

Comments

[Joseph]

Worked! But I now a new question arises. What is 'cfg80211' and it's purpose?

[Nathan McCoy]

A quick search for this module seems to show it is related to WiFi communication between user <-> kernel space. I would suggest reloading this module and seeing if WiFi works or not. you can also run dmesg to get some debugging info about any errors that may arise.

[Andrew Falanga]

Alternatively, you could use readlink and resolve the target of /sys/class/net/<intf>/device/driver. For example, on my system (I still use the ethN moniker) readlink /sys/class/net/eth0/device/driver resolves to ../../../bus/pci/drivers/e1000e. Thus, the driver is e1000e.ko. You would load via modprobe e1000e. You would need to know the interface name for your WiFi device.