/**
@brief		try to transmit all IPC frames in an skb_txq to CP

@param mld	the pointer to a mem_link_device instance
@param dev	the pointer to a mem_ipc_device instance

@retval "> 0"	accumulated data size written to a circular TXQ
@retval "< 0"	an error code
*/
static int tx_frames_to_dev(struct mem_link_device *mld,
			    struct mem_ipc_device *dev)
{
	struct sk_buff_head *skb_txq = dev->skb_txq;
	int tx_bytes = 0;
	int ret = 0;

	while (1) {
		struct sk_buff *skb;

		skb = skb_dequeue(skb_txq);
		if (unlikely(!skb))
			break;

		ret = txq_write(mld, dev, skb);
		if (unlikely(ret < 0)) {
			/* Take the skb back to the skb_txq */
			skb_queue_head(skb_txq, skb);
			break;
		}

		tx_bytes += ret;
	}

	return (ret < 0) ? ret : tx_bytes;
}
static int tx_frames_to_dev(struct mem_link_device *mld,
			    struct mem_ipc_device *dev)
{
	struct sk_buff_head *skb_txq = dev->skb_txq;
	int tx_bytes = 0;
	int ret = 0;

	while (1) {
		struct sk_buff *skb;
#ifdef DEBUG_MODEM_IF_LINK_TX
		u8 *hdr;
		u8 ch;
#endif

		skb = skb_dequeue(skb_txq);
		if (unlikely(!skb))
			break;

		ret = txq_write(mld, dev, skb);
		if (unlikely(ret < 0)) {
			/* Take the skb back to the skb_txq */
			skb_queue_head(skb_txq, skb);
			break;
		}

		tx_bytes += ret;

#ifdef DEBUG_MODEM_IF_LINK_TX
		hdr = skbpriv(skb)->lnk_hdr ? skb->data : NULL;
		ch = skbpriv(skb)->sipc_ch;
		log_ipc_pkt(ch, LINK, TX, skb, hdr);
#endif

		dev_kfree_skb_any(skb);
	}

	return (ret < 0) ? ret : tx_bytes;
}