Ps3 – How to pass the bathroom part in the mission “Enter the Bank” undetected

I think it could be a fire button, the one you shoot with, R1 probably?

Taking a look at the http://battlefield.wikia.com/wiki/Suppressive_Fire posted by Foxtrot, the wiki says as follows:

To suppress a target, simply shoot at them. The projectiles do not have to hit the target, they only have to pass through or land in a certain radius around the target.

Since the text specifically talks about hitting the target, i take that to mean suppression fire is missed shots on target.

If you take that as how the game treats suppression fire, then all shots that do not hit the enemy/enemy vehicle would be considered a missed shot.