Upgrade from 1.12 piwik

currently I am running Piwik 1.12 on redhat 2.6 with PHP Version 5.3.3 and mySQL versin 5.3.3
To which version of Piwik can I upgrade without lot’s of issues?
I have seen the ‘one click Piwik update button’ of course.
Would I need to upgrade the php and mysql versions as well?