He wasn't in the list of attendees but this passage:

Somewhere around this time, Hitler resolved that the Jews of Europe were to be exterminated immediately, rather than after the war, which now had no end in sight.[33][a] At the Reich Chancellery meeting of 12 December 1941 he met with top party officials and made his intentions plain.[34] The war was still ongoing, and since transporting masses of people into a combat zone was impossible, Heydrich decided that the Jews currently living in the General Government (the German-occupied area of Poland) would be killed in extermination camps set up in occupied areas of Poland, as would Jews from the rest of Europe.[35]

Is what I was referencing. Wannsee went into more of the specifics but Hitler still made his intentions known. Hitler, at the earlier meeting, declared that now was the time to exterminate the Jewish population. Yes, he didn't attend the Wannsee Conference but told Heydrich to begin executing them.

To say Hitler had no idea or order of genocide doesn't make any sense (I guess in my opinion). Yes, he wasn't running the camps. Yes, he wasn't choosing the method by which to kill those in the concentration camps but he was very much involved with the decision to kill all of the Jews.