All grounds for relief available to a petitioner under this rule must be raised in his original petition. Any ground finally adjudicated on the merits or not so raised and knowingly, voluntarily and intelligently waived in the proceeding that resulted in the conviction or sentence, or in any other proceeding the petitioner has taken to secure relief, may not be the basis for a subsequent petition, unless the court finds a ground for relief asserted which for sufficient reason was not asserted or was inadequately raised in the original petition.
Ind. R. Post-Convic. Rlf. 8