we always set ->SCp.ptr to physical address of buffer; for DMA that's
just what we need, but we end up using it as virtual address in PIO
case of esp_do_data(), with obvious breakage as soon as memory mapping
becomes non-trivial.  The fix is obvious.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>