Re: [RFC PATCH 0/3] usbnet: support runtime PM triggered by link change

On Sunday 16 September 2012 01:48:16 Ming Lei wrote:

Hi,

Currently only very few usbnet devices support the traffic based
runtime PM, eg. wake up devices if there are packets to be transmitted.

For the below situation, it should make sense to runtime suspend usbnet
device to save power:
        
        - after network link becomes down

Basically cool design, but it raises two fundamental questions
and some detail questions.

This patch implements the runtime PM triggered by network link change
event, and it works basically on asix usbnet device after a simple
runtime PM test.

1) Does it actually save power? You are constantly waking up a CPU.

From that perspective it is possible that leaving on the ethernet is actually

better in terms of power. Only measurements can answer that question.

2) Do we have many devices that would be serviced with this approach?

	Regards
		Oliver