i agree with Sangkha, once the main domain banned, the whole domain is banned, including the subdomain
Yes, your whole domain is banned, including any sub domains. You can try and appeal your ban here: https://support.google.com/adsense/bin/request.py?contact_type=policy_violation_appeal but don't get your hopes up.
once you're banned on main site, don't even bother using it again on anywhere else because your account will be banned permanently
I have fallen foul of Google AdSense. I have various websites that contain Google AdSense and I make a nice tidy amount each year, more than enough to pay for a dedicated server with quite a lot much revenue at all, maybe a few pound a week, it's another one of my websites that earns me enough money to pay for my dedicated server, plus quite a lot leftover, mind you that website receives anywhere between 2000 and 3000 each day. The website that got banned probably receives about 300 hits a day. Anyway, Google sent me a message telling me that the website has been excluded from Google AdSense because I had broken their policy. Thankfully they gave me a link to the offending page, it was actually a jokes page that contains all sorts of jokes, many of an adult in content. I'm pretty amazed that I got banned for this reason, it is not as if there was any kind of explicit sexual content on the page. I have found myself that some people are getting kicked or no apparent reason, many of these websites are small and I don't suppose Google want to bother with them. Anyway, I removed AdSense from all of these pages on my website and asked them to review it. They did indeed review it again but told me that it is still broke their policy I feel like I'm dealing with the dictatorship, who are Google to tell me what I can and cannot have. It's quite simple, I won't put Google AdSense on any page that contains adult content of any type. I'm sure that if you type into Google "donkey sh***ing" you'll find something dubious (not that I am into that kind of thing )
Google doesn't like creating sub-domain. It is a unethical way of seo. So, next time be cautious about it.