Re: [PATCH] lan78xx: Protect runtime_auto check by #ifdef CONFIG_PM

From: Oliver Neukum
Date: Mon Mar 21 2016 - 13:34:41 EST

On Mon, 2016-03-21 at 10:57 -0400, Alan Stern wrote:

> One possible solution is to export a sysfs parameter to prevent
> statistics collection (or more generally, to change the interval at
> which it occurs).

Surely, not performing a task can hardly be beaten in terms of power
consumption. That is not meant to be flippant, but I think these
issues are orthogonal. The question of how much to do doesn't
solve the question of doing efficiently what we do.

> But checking the runtime_auto flag is probably not a great idea. Even
> if it isn't set, collecting statistics is likely to wait up a device
> that otherwise would have remained suspended.
> Perhaps the best solution is to collect the statistics only when the
> device is not suspended or is about to suspend.

If we know when the next activity will come, why not pass this
information down?