Availability of XO-1.5 ATest-2 machines

Benjamin M. Schwartz bmschwar at fas.harvard.edu
Mon Jul 20 15:26:23 EDT 2009

david at lang.hm wrote:
> On Mon, 20 Jul 2009, Paul Fox wrote:
>> chris wrote:
>>> Hi,
>>>    > my understanding from watching discussions here was that when the
>>>    > system went to sleep it powered down the display, because there
>>>    > was no way to set a timer to wake the system up a little later to
>>>    > then turn off the display.
>>> Your understanding is incorrect, I'm afraid.  We do not power down the
>>> display going into idle-suspend.
>> but to be clear, david's right that once the laptop's in this
>> state there's no way to turn off the screen automatically later
>> on -- the system must be re-awakened with user input, and then
>> put to sleep in one of the usual (power switch or lid) ways.
>> this is simply a limitation of current s/w.
> is this just a software limitation? 

Yes. You can use the rtcwake command to set wakeup timers for the future
from userspace.  However, my impression is that this is only safe if the
timer is at least 2 seconds in the future at the time of suspend, due to a
potential race with the EC.

OHM could be modified to make use of rtcwake to, for example, wake up from
sleep after 30 minutes, turn off the backlight, and suspend again.  It
simply hasn't been done.


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