#11644 LOW 1.75-so: Camera LED may flash briefly during resume

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#11644: Camera LED may flash briefly during resume
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           Reporter:  greenfeld  |       Owner:  corbet                           
               Type:  defect     |      Status:  new                              
           Priority:  low        |   Milestone:  1.75-software                    
          Component:  kernel     |     Version:  Development build as of this date
         Resolution:             |    Keywords:                                   
        Next_action:  diagnose   |    Verified:  0                                
Deployment_affected:             |   Blockedby:                                   
           Blocking:             |  
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Changes (by wad):

  * owner:  => corbet
  * milestone:  1.75-hardware => 1.75-software


Comment:

 I have double-checked this with an oscilloscope (trace attached).

 Yellow is VCXO_EN, when it goes high, the main core starts coming out of
 suspend.

 Blue is DDR3 CKE, it is asserted high for any memory access.   It signals
 the first execution of code by the resumed main processor.    When it
 starts being asserted almost all the time is probably when the main
 display is turned back on.

 Magenta is EN_CAM_PWR.   Note that it stays low throughout the suspend,
 then for some reason the kernel turns it on in early resume, then turns it
 off later in the resume.

 Reassigning to a kernel hacker...

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Ticket URL: <http://dev.laptop.org/ticket/11644#comment:3>
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