We still use the interrupt filter due to performance problems that show up if
we don't. The main problem seen is that, due to the interrupt being edge
triggered, we occasionally miss interrupts which leads us to not notice that
we can transmit more packets. Using the new approach, which just schedules
a task on a taskqueue, we are guaranteed to have the task run even if the
interrupt arrived while we were already executing. If we were to use an
ithread the system would mask the interrupt while the handler is run and we'd
miss interrupts.
sn(4) driver and also looking at newer drivers. The reason for the rewrite is
to support MII and to try and resolve some performance issues found when trying
to use the sn(4) driver on the Gumstix network boards.
For reference, the SMSC LAN91C111 is a non-PCI ethernet part whose lineage
dates back to Ye Olde Days of ISA. It seems to get some use in the embedded
space these days on parts lacking on-board MACs or on-board PCI controllers,
such as the XScale PXA line of ARM CPUs.
This also includes a driver for the SMSC LAN83C183 10/100 PHY.
Man page to follow.
