Auto fill billing information in cc avenue payment
Finally found the answer with help of this issue queue https://www.drupal.org/node/2310505

In commerce_ccavenue.module added few lines inside commerce_ccavenue_redirect_form($form, &amp;$form_state, $order, $payment_method)

$billing_address = $wrapper-&gt;commerce_customer_billing-&gt;commerce_customer_address-&gt;value();
  $order_data = array(
    'merchant_id' =&gt; $payment_method['settings']['merchant_id'],
    'amount' =&gt; $wrapper-&gt;commerce_order_total-&gt;amount-&gt;value() / 100,
    'order_id' =&gt; $order-&gt;order_id,
    'cancel_url' =&gt; url('checkout/' . $order-&gt;order_id . '/payment/back/' . $order-&gt;data['payment_redirect_key'], array('absolute' =&gt; TRUE)),
    'redirect_url' =&gt; url('checkout/' . $order-&gt;order_id . '/payment/return/' . $order-&gt;data['payment_redirect_key'], array('absolute' =&gt; TRUE)),
    'working_key' =&gt; $payment_method['settings']['working_key'],
    'access_code' =&gt; $payment_method['settings']['access_code'],
    'language' =&gt; 'EN',
    'currency' =&gt; $currency_code,
    'billing_name' =&gt; $billing_address['name_line'],
    'billing_address' =&gt; $billing_address['thoroughfare']. ' ' . $billing_address['premise'] . ' ' . $billing_address['sub_premise'],
    'billing_zip' =&gt; $billing_address['postal_code'],
    'billing_city' =&gt; $billing_address['locality'],
    'billing_state' =&gt; $billing_address['administrative_area'],
    'billing_country' =&gt; 'India',
  );


These lines are missing inside commerce_ccavenue_redirect_form($form, &amp;$form_state, $order, $payment_method). Works fine after adding those lines.