joomla getListQuery limit 20 problem

 JModelList::getListQuery - How to expand limit.

I'm using the following code in my Component Model to retrieve my database array

protected function getListQuery()
        {
                // Create a new query object.          
                $db = JFactory::getDBO();
                $query = $db->getQuery(true);
                // Select some fields
                $query->select('product_id,product_sku,product_s_desc,product_thumb_image');
                // From the virtuemart product table
                $query->from('#__vm_product');
                $query->where('product_in_stock >0','product_publish =1');
                $query->limit('0,40');
                return $query;
        }

the problem with this is that it's only return me 20 results at a time.  And I need this to be unlimited.   The solution for this I found in this post JModelList::getListQuery  limits to 20 only
What you need to do is add this code above the function getListQuery
protected function populateState()
{
        $this->setState('list.limit', 0);
}

and it'll work like magic :)