On Thu, 2014-10-30 at 18:41 +0100, Pavel Machek wrote: > On Thu 2014-10-30 16:15:15, Bastien Nocera wrote: > > On Thu, 2014-10-30 at 11:05 -0400, Theodore Ts'o wrote: > > > On Thu, Oct 30, 2014 at 03:45:02PM +0100, Bastien Nocera wrote: > > > > > Actually Maemo people (on Nokia N900 and friends) got it right: unlike > > > > > android devices, it does not suspend to RAM at any point, and still > > > > > has reasonable battery life. > > > > > > > > Android devices don't suspend to RAM. Neither do Tizen devices AFAIK. > > > > > > Actually, Android devices have historically always suspended the CPU > > > whenever there wasn't a wakelock keeping the device to suspend. You > > > might not consider this "suspend to RAM" but in fact it uses the > > > identical kernel and hardware facilities as the legacy "suspend to > > > RAM" mechanism. > > > > I wouldn't consider this "suspend to RAM", but that's because I expect > > the firmware to implement most of that. Anyway, that's splitting > > hair. > > Could you rephrase that? > > Anyway, this is "echo mem > /sys/power/state" or > suspend-to-RAM. Android does the same, with more tricky wakeup logic. > > > > > I don't think anyone was discussing cell phones in particular in this > > > > thread, and knowing when user-space got woken up because of the baseband > > > > processor having information for us would still be useful. > > > > > > It matters because for laptops, what's important is whether the lid is > > > closed or not. Whether and how the laptop was "woken" is really > > > beside the point, as others have argued. Your counter argument is > > > that tablets don't have lids. But tablets are going to be using > > > schemes similar to Android, Tizen, and Maemo, and they are *not* going > > > to be using the legacy suspend-to-RAM model, because it's not > > > sufficiently good at power saving. > > > > There are plenty of tablets around that aren't Android devices. There > > are plenty of laptops that can be switched to a tablet mode for which > > this wouldn't apply either. > > Yes, still the right question is "was the power button pressed while > userland was suspended" not "was the system woken by power > button"...
"Was the power button pressed while userland was suspended" is presumably also racy. > and yes, I guess kernel should add the "power button" event > to the input queue, even if that press was used to wake up the system. And how would one know whether to suspend or resume in this case? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
