question about ethernet/tundra/tsi108_eth.c

The driver ethernet/tundra/tsi108_eth.c seems to be inconsistent about how
it shares buffers with the device.  In the open function (tsi108_open), it
uses virt_to_phys.  In the refill function (tsi108_refill_rx), it uses
dma_map_single.  However, there doesn't seem to be any dma_unmap_single
anywhere.

I see that this is not a very actively maintained driver, but I am
interested in the general question of how this works.

thanks,
julia