Andy Gospodarek wrote:

This patch added the TxDescPower parameter to the e1000 module.  This
parameter represents the size-order of each transmit descriptor.  The
valid size for descriptors would be 2^7 (128) - 2^12 (4096) bytes each.
As this value decreases one may want to consider increasing the
TxDescriptors value to maintain the same amount of frame memory.  This
patch does not change the defaults for any particular hardware model, so
this will not have an effect on existing users.

The purpose of the patch is to address Tx Timeouts on 82545 and 82546
chips that can show up during high-stress situations.  Decreasing the
transmit descriptor size can shorten the amount of time that will be
spent DMAing frames to the hardware and can reduce the likely-hood that
Tx Timeouts will occur.

Signed-off-by: Andy Gospodarek <andy@greyhouse.net>
---
 drivers/net/e1000/e1000.h       |    6 ++++++
 drivers/net/e1000/e1000_main.c  |   12 ++----------
 drivers/net/e1000/e1000_param.c |   33 +++++++++++++++++++++++++++++++++++
 3 files changed, 41 insertions(+), 10 deletions(-)

I don't see why a module parameter is needed.  In practice, nobody will 
ever think about this option, much less use it.