Michael Brown
3915b660fd
[hw] Eliminate polling while waiting for window to open
Polling for the data-transfer window to become open is wasteful. We
can eliminate the polling loop by using hw_step() as the handler for
an xfer_window_changed() event.
If the window is already open at the time of instantiation, then
xfer_window_changed() may never be called. We can cover this case by
using hw_step() as the step() method of a one-shot process. Since the
signature for an xfer_window_changed() method is identical to the
signature for a process step() method, the same function can be used
for both.
Signed-off-by: Michael Brown <mcb30@ipxe.org>