Drivers for Broadcom BCM43142 on Ubuntu 14.04 (Trusty Tahr)

OK, so I finally fixed this :D

First here's what I learnt in the process:

1. NEVER ram your OS with different drivers or modules haphazardly until your problem gets fixed, at least not without a) Knowing what / why you are doing, and b) MOST IMPORTANTLY How to undo the same.

2. Whenever you try a different driver, module, or package, first uninstall the package that you previously installed for the same purpose.

And lots of thanks to @chili555 who pointed out that the leftover from a previous package was the reason.

So what I did was:

1. I tried installing bcmwl-kernel-source on a live run of Ubuntu 14.04 (with my LAN cable) and checked if WLan works now. (And yeah, it did confirm that Ubuntu 14.04 / BCM43142 / bcmwl-kernel-source were not the problem.)

2. I went to /etc/modprobe.d and cross checked the files there with my hard disk installation's version of the same folder.

3. This /etc/modprobe.d directory contains configuration files which contain blacklisting information for different modules. I made a note of the available files and later removed what was not available here from my hard disk installation's version of the same folder too.

4. I went to /lib/modules/3.*/updates/. This is the directory that stores all your modules (wl, b43, etc. ... ) and the one that I messed up with various custom patched versions of wl modules listed in various forums.

5. After cross checking with my hard disk installation's version of lib/modules/3.*/updates/, I manually removed all Bluetooth / wireless / dkms / wl / (and in particular one mac80211) and cleaned up any other modules that are related to wlan.

6. I finally replaced (did a recursive copy onto) the /etc/modprobe.d and /lib/modules/3.*/updates/ directories (of my hard disk installation) with the same directories from the live OS.

7. Reboot

8. Do sudo apt-get install bcmwl-kernel-source. This is the official working driver for BCM43142 for Ubuntu 14.04.

9. Reboot and sudo modprobe wl and viola, wireless was working!

And finally sincere apologies to all my cross-posting, reposting, spamming IRCs with this question repeatedly. :P

NOTE: Replacing /removing your hard disk installation files is recommended only for those who installed your OS recently. Otherwise there is a risk that you could replace / remove files / modules that may have been installed for other devices which may be irrelevant to this issue.

Thanks again to chili555 :)

EDIT I recently updated my kernel to support the DisplayLink driver for my USB monitor and bam the wifi was gone.

A blind attempt at re-installing bcmwl-kernel-source threw the following error in the build log.

"alloc_netdev" requires 4 arguments, but only 3 given

Turns out the driver was not updated for the upgraded kernel (version 3.18). A bit of googling let me to this post -

https://bugs.launchpad.net/ubuntu/+source/bcmwl/+bug/1358966

Where there are links available to patched versions of wl, which works with the upgraded kernel.

I manually downloaded and installed this guy and wifi was restored.

Now I can go back to browsing lolcats in peace. Amen.

I too had the same trouble when installing Linux Mint, Ubuntu 13.10 and 14.04. I had to use a LAN cable or USB tethering from my phone to get bcmwl-kernel-source installed which seemed to be the only working wireless driver for my DELL inspiron 15.

however i was able to see the bcmwl-kernel-source in the additional drivers section of the software updates after running

sudo apt-get update

from the terminal after establishing internet connection via LAN or USB tethering and you will see the additional drivers listed from where i was able to install the driver pretty easily.