Sort results by name & asc order on homepage

Since you only want to hook into the posts on your homepage, I think you only need something like this:

<?php
add_action( 'pre_get_posts', 'my_change_sort_order'); 
function my_change_sort_order( $query ){

   if ( ! is_admin() && $query->is_main_query() ) :

      if ( is_front_page() ) :
         //Set the order ASC or DESC
         $query->set( 'order', 'ASC' );
         //Set the orderby
         $query->set( 'orderby', 'title' );
      endif;

   endif;
}
?>