i2c stop working

that's a good point about today's problems on raspberry pi related sites. Let's see what the future brings to us...

I was having the same issue with a tnc-pi board using i2c, after three days finally found a solution.  After adding  "dtparam=i2c1=on" to the  /boot/config.txt file and rebooting all was back.  Later found my usb to serial was not found.  Removed the dtparam line, and added "device_tree=" instead.  There is a discussion on http://www.raspberrypi.org/forums/viewtopic.php?p=675658#p675658 that I can't get to at the moment that covers what changed. 

For now all my hardware is back running.

There is a discussion on http://www.raspberrypi.org/forums/viewtopic.php?p=675658#p675658 that I can't get to at the moment that covers what changed.

With today's problems I found Google archive function very useful. Just google this url, click the little down-facing green arrow next to the url in the first result and select Archive.

Cool.  That gives me a couple ideas too.

Thank god this solution is on this forum and not on the raspberry pi one.....

Thanks: "device_tree= " in /boot/config.txt works for me.

I haven't a clue why giving it an empty device tree would make things work all of a sudden, but it does.

Thanks Roger, it worked for me as well !

Just found out a few things that i believe will be helpful and that appear to be the best way to solve these problems:

As i have pointed out earlier, the problems appear to be due to changes in the kernel after updating the Raspbian software by issuing these commands:

sudo apt-get update

sudo apt-get dist-upgrade

and rebooting. This procedure is highly recommended to keep your raspi updated with the latest updates that have been thoroughly tested (and we need to avoid using the "sudo rpi-update" command because that is not meant to be used by normal users but rather by developers and testers). But after doing this the problems with the drivers start because the new kernel comes configured to use the new device tree by default (rather unfortunate, in my opinion). Ok then. What to do? Well i found out that there is also a new update available for raspi-config, and that has a configuration setting which allows you to set up your raspi correctly depending on which device solution you prefer to use. So the first thing you need to do after upgrading the raspi software is to upgrade your raspi-config tool. This is done from the raspi-config tool, and you start the tool with this command:

sudo raspi-config

When the tool starts, you need to navigate down to the "Advanced Options" choice using the arrow-down key, then press the "Tab" key to highlight "Select", then hit "Enter". In the Advanced Options meny, navigate down to the "Update" choice using the arrow-down key, then hit the "Tab" key to highlight "Select", then hit the "Enter" key. This starts the process of updating the tool. When it is finished you will be returned to the raspi-config tool. Back in the tool, navigate down to the "Advanced Options" with the down-arrow, hit the "Tab" key to highlight "Select", hit "Enter", navigate down to "Device Tree" with the down-arrow key, hit "Tab" to highlight "Select", hit "Enter", hit the "Tab" key until "No" is highlighted (in response to the question "Would you like the kernel to use Device Tree?"), then hit "Enter". Hit "Enter" again when it indicates that "Device Tree is disabled" and "Ok" is highlighted. "Tab" to "Finish", then hit "Enter". Now reboot again:

sudo reboot

When the raspi is up again and you log in everything should work again.

I had the same story as everyone else. Everything was working, ran rpi-update, did the updates, then nothing wasn't.  Spent three days doing searches, that eventually led me to the raspberry pi forum.  The empty list from the post cause's it to revert to the old way of doing things.  No more nodes, but a device tree.  I don't know enough about the pi and linux to explain it, just enough to know it solved my problems.