>> You can gain a lot of performance by not using Tx interrupts, on
>> devices that can do it.
>
> Is there another driver that does this that I might look off of?

The followings are good example to learn smart NetBSD drivers.
- sys/dev/pci/if_pcn.c
- sys/arch/powerpc/ibm4xx/dev/if_emac.c
- sys/arch/mips/alchemy/dev/if_aumac.c
There three are mostly made by the same person and show the
way how NetBSD netif driver should be constructed.  I recommend
you to rewrite your epe.c driver.  Since the HW is ARM SoC dependent
you could be benefited to "break" NetBSD portablity for performance
tradeoff.

Toru Nishimura/ALKYL Technology, Linux does not save a company; d|i|g|i|t|a|l.