On 13.12.2011 03:50, YongHyeon PYUN wrote:
On Tue, Dec 13, 2011 at 12:56:22AM +0100, Stefan Bethke wrote:
I'm currently writing a driver to configure an ethernet switch chip (see
TL-WR1043ND on -embedded).
I noticed that there doesn't seem to be a way to power down a phy right now
through the ifconfig media command.
Would there be objections to extend the media subtype definitions to include an "off",
"poweroff" or "down" media subtype, and add code to the relevant phy drivers to power
down the phy for this media subtype?
The difference between media subtype "none" and this new one would be that there will be
no link, even if there is a physical connection. With media subtype "none", a 10 MBit/s
half-duplex connection is established, potentially confusing the remote end about the availability
of this link. On the local side, the link is down, so no packets are exchanged.
I think "none" means "isolated" so should have no established link
and probably you can also power down the PHY.
I vaguely guess the PHY of switch chip does not correctly support
isolated mode so you may have wanted to power down.
There is a difference between "none" with "status: no carrier" where no ethernet
connection is established, but can be brought up the moment a cable is plugged
in,
and "poweroff" where the PHY itself is powered down and won't notice a cable
being
plugged in unless configure to auto-select or a particular speed.
Considering that PHY devices are relatively power hungry a poweroff state may be
quite useful to conserve battery power.
--
Andre
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