From: Anton Vorontsov <redacted>
Date: Wed, 30 Jun 2010 20:38:04 +0400

On Tue, Jun 29, 2010 at 03:16:26PM -0700, David Miller wrote:

quoted

I really don't see any value at all to this config option,
the errata fixup code should be there all the time.

Well, at least for eTSEC76 erratum (patch 2/3) we have to touch
fast path (i.e. start_xmit), so I just wanted to make zero
overhead for controllers that don't need any fixups.

Not that there's much of the overhead in a single additional
'if' condition, no. ;-)

The register accesses will dominate the costs with this chip.

The only case where a if() test is going to potentially create
some practical performance impact is if the TX is performed
purely using changes to a shared memory data structure and
absolutely no MMIO register reads or writes.