tx_read
val = tx_read(tx, ADV748X_CSI_FS_AS_LS);
priv->tx_count = priv->tx_read = priv->tx_write = 0;
while (priv->tx_read != rptr) {
skb = priv->tx_skbs[priv->tx_read];
status = priv->tx_ring[priv->tx_read].header.raw;
if (priv->tx_read == priv->tx_write)
DPRINTK("Auchi! tx_read=%d,tx_write=%d,rptr=%d?\n", priv->tx_read, priv->tx_write,rptr);
priv->tx_skbs[priv->tx_read] = NULL;
priv->tx_ring[priv->tx_read].header.raw = 0;
priv->tx_read = (priv->tx_read+1)&(TX_RING_ENTRIES-1);
unsigned long tx_read, tx_write, tx_count;