First post and probably a dumb question. But can someone tell me what the small circular knob is on the A320’s corner window pillars are? For lack of a better explanation, it looks like a black and white “ying yang” symbol, with a black rectangular switch underneath it. It’s INOP in both the MS and FBW versions.
I know it doesn’t work, but having to look at it the entire flight without knowing what it is, is driving me nuts. Tried searching and Google and couldn’t find an answer.
I think they are controls for the captain’s and first officer’s reading lights, on the left and right respectively.
It’s the dimmer for the reading lights which you turn on/off on the switch below the dial. It works on the Fenix. 
Thanks for the responses! Well, I guess I won’t be doing much reading in the dark then haha
Get the Fenix and you can read in the dark and a whole lot more 
Seriously…it’s the best money I’ve spent on an airplane addon. The FBW is great, but the Fenix really is another level and almost every switch/button works.