Message-ID: <1414764089.2406.74.camel@hadess.net>
Subject: Re: A desktop environment[1] kernel wishlist
From: Bastien Nocera <hadess@hadess.net>
To: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Cc: John Stultz <john.stultz@linaro.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Date: Fri, 31 Oct 2014 15:01:29 +0100
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On Thu, 2014-10-30 at 23:25 +0000, One Thousand Gnomes wrote:
> O> The kernel receives an interrupt, likely on a different device. Again,
> > I'm talking about "legacy" devices, for which suspend is actually a
> > state. If the device is only in low-power mode, you'd probably get the
> > event on the input device, which is accessible from user-space.
> 
> I don't believe so - the firmware ate it.
> 
> > Knowing why the Wi-Fi card woke up is also important when there isn't a
> > full "suspend" state. As was mentioned, it's useful for power debugging,
> > but it's also useful because that tells things outside the network card
> > driver what happened.
> 
> Wifi devices that are smart generally have a fair bit of info they
> provide themselves on this. In particular if you are using a deep idle
> type behaviour they may well wake every minute or so just to poke a
> packet out to keep any NAT mapping alive.
> 
> > As I mentioned in more recent emails on this thread, maybe we don't want
> > to know what woke the system up, but knowing that a wake-up event
> > occurred on this device, at this time, would allow us to make the
> > software act accordingly. The fact that we don't know that means that we
> > cannot take appropriate action.
> 
> What woke the system up may also not be a singular item. Suppose the
> alarm goes off as the user opens the lid and the wireless gets a wakeup
> packet in the same window ?

Then each one of those devices would have their own wakeup reason set,
with a timestamp.

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