Developer Forum

Definitely matters. Switch renegotiation can take a while, and you must
take into account the common case of interface bouncing (immediate down,
then up).

Hoards actively complained the few times we experimented with this,
because of e.g. DHCP's habit of bouncing the interface, which resulted
in PHY power bouncing, which resulted in negotiation, which resulted in
an excrutiating wait on various broken or stupid switches.

Overall, this may be classed with other problems of a similar sort: we
can power down a PHY, but that removes hotplug capability and extends
partner/link negotiation time.

Like SATA, we actually want to support BOTH -- active hotplug and PHY
power-down -- and so this wanders into power management policy.

Give me a knob, and we can program plenty of ethernet|SATA|USB|...
drivers to power down the PHY and save power.

Jeff


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