My camera won't stop looking up

[TheKlenkster]

So I was playing portal on steam with my PS4 controller connected via the charging cable. But the camera was constantly looking up even when I corrected it. It made it extremely difficult to plant portals. Can someone please tell me how to fix this?

[Quint]

Try messing with analog dead zone.

[The Archmage]

Had same issue except camera spun to the left constantly.
Right click on Portal in your library and go to Manage > Controller layout, then remove the mappings for the centre tracking pad so that it does nothing. Look for anything other than the right trigger being set to move the camera and set the way to 'none' instead so only the right trigger has control, as you would expect for an older PS controller.
You may also have two buttons set for 'crouch' or 'pick up item', map those moves as you like as well while you're there.