Re: [RFC PATCH net-next 1/8] ethtool: Add ability to control transceiver modules' low power mode

On Tue, 10 Aug 2021 22:00:51 +0000 Keller, Jacob E wrote:

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Jake do you know what the use cases for Intel are? Are they SFP, MAC,
or NC-SI related?  

I went through all the Intel drivers that implement these operations and
I believe you are talking about these commits:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c3880bd159d431d06b687b0b5ab22e24e6ef0070
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d5ec9e2ce41ac198de2ee18e0e529b7ebbc67408
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ab4ab73fc1ec6dec548fa36c5e383ef5faa7b4c1

There isn't too much information about the motivation, but maybe it has
something to do with multi-host controllers where you want to prevent
one host from taking the physical link down for all the other hosts
sharing it? I remember such issues with mlx5.
  

Ok, I found some more information here. The primary motivation of the
changes in the i40e and ice drivers is from customer requests asking to
have the link go down when the port is administratively disabled. This
is because if the link is down then the switch on the other side will
see the port not having link and will stop trying to send traffic to it.

As far as I can tell, the reason its a flag is because some users wanted
the behavior the other way.

I'm not sure it's really related to the behavior here.

For what it's worth, I'm in favor of containing things like this into
ethtool as well.

I think the question was the inverse - why not always shut down the
port if the interface is brought down?