Auto-populate page title of previously-viewed page in a Gravity Form field

functions.php

<?php
function awi_autopopulate_workshop_title( $value ){
   $referer_id = url_to_postid( wp_get_referer() );
   $workshop_title = get_the_title( $referer_id );
   return $workshop_title;
}
add_filter( 'gform_field_value_workshop_title', 'awi_autopopulate_workshop_title' );

// Usage: 
// Add code to functions.php or similar
// Under "Advanced" tab for the given field in the GF UI, tick the "Allow field to be populated dynamically" box
// Add "workshop_title" (no quotes) to the "Parameter Name" input