netdev - Re: [PATCH] lan78xx: Protect runtime_auto check by #ifdef CONFIG

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Date:	Mon, 21 Mar 2016 18:34:30 +0100
From:	Oliver Neukum <oneukum@...e.com>
To:	Alan Stern <stern@...land.harvard.edu>
Cc:	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Woojung Huh <woojung.huh@...rochip.com>,
	Microchip Linux Driver Support <UNGLinuxDriver@...rochip.com>,
	"David S. Miller" <davem@...emloft.net>,
	Guenter Roeck <linux@...ck-us.net>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>, netdev@...r.kernel.org,
	linux-usb@...r.kernel.org, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] lan78xx: Protect runtime_auto check by #ifdef CONFIG_PM

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?

	Regards
		Oliver