[ltp] S2D breaks S2RAM

[Henrique de Moraes Holschuh]

On Fri, 10 Apr 2009, Yves-Alexis Perez wrote:
> On mer, 2009-04-08 at 15:28 -0300, Henrique de Moraes Holschuh wrote:
> > On Wed, 08 Apr 2009, Nils Faerber wrote:
> > > I also see a difference in power consumption with S2D!?
> > 
> > Whatever you do, never use 'platform' (S4) in a thinkpad.  Our kernel is not
> > up to it yet.  Use 'shutdown' (S5).
> 
> Erf, it's not really widely know, it seems. Well, I mean, I didn't :)
> Is there a way to tell the kernel about that once for all? Or one should
> do an echo shutdown > /sys/power/disk at each boot?

I think you will actually have to mess with HAL if you use your distro's
infrastructure for sleeping.

It is not that S4 doesn't work.  It is that you cannot trust it to turn
things off properly, and the Lenovo thinkpads have a history of not always
doing it on the BIOS either (so, stuff remains on and drawing power...).

For a while, not even S5 was safe on a few X60 I think.  I have no idea what
caused _that_, and what fixed it.

Well, *test* S4 for your particular thinkpad.  If it works well and doesn't
drain the battery, by all means use it.  Just keep an eye on it every time
you update the BIOS.

I should have said "when in doubt, never use S4 in a thinkpad..."

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh