#4606 NORM -: XO can't resume from suspend at a particular time set by software

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#4606: XO can't resume from suspend at a particular time set by software
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  Reporter:  gnu          |       Owner:  wad  
      Type:  enhancement  |      Status:  new  
  Priority:  normal       |   Milestone:       
 Component:  hardware     |     Version:       
Resolution:               |    Keywords:  power
  Verified:  0            |  
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Changes (by gnu):

  * milestone:  FutureFeatures =>


Comment:

 Richard Smith says he can probably help us fix this by using a higher
 resolution timer in the EC to wake us up.  Copying from emails with MLJ:

 gnu said:
 > So much work has been done on this, yet so much remains.  When the XO
 > suspends, it can't resume at a preset time, except on 1-second
 > boundaries.  So if the kernel knows it has nothing to do for 2.7
 > seconds, it can't suspend for 2.7 seconds.  It can't even suspend for
 > 2 seconds, since it will wake when the battery backup realtime clock
 > ticks into the next second, which will drift against the Unix time.
 > The kernel can (and will have to) track this.  I discovered this last
 > week when looking into automatic suspend.  Richard Smith can probably
 > fix this by using a higher resolution timer in the EC to wake the
 > system, or by tristating a gpio so we can reuse it for an MFGPT
 > output/feedback-input during suspend.

 MLJ said:
  I'm sitting next to Richard Smith who agrees about the timing issues.


 Trac won't let me keep the milestone as "FutureFeatures"; for somebody
 with my privileges, there's no such milestone :-) though there's a "Future
 Release".  Personally I think this will need fixing to make suspend-on-
 kernel-idle useful for much of anything; we can't go to sleep unless we
 can predict with high probablilty exactly when we'll be waking up (at the
 latest).  It's back to a blank milestone.

-- 
Ticket URL: <http://dev.laptop.org/ticket/4606#comment:4>
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