#9692 HIGH 1.5: XO-1.5 needs delay in powering off the internal SD card

[Zarro Boogs per Child]

#9692: XO-1.5 needs delay in powering off the internal SD card
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           Reporter:  wad                  |       Owner:  rsmith      
               Type:  enhancement          |      Status:  new         
           Priority:  high                 |   Milestone:  1.5         
          Component:  embedded controller  |     Version:  1.5-B3      
         Resolution:                       |    Keywords:  sdmmc XO-1.5
        Next_action:  design               |    Verified:  0           
Deployment_affected:                       |   Blockedby:              
           Blocking:                       |  
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Comment(by rsmith):

 An implementation for this was discussed here in the 1cc offices and I
 started to add it into the EC code base but I realized that there's a good
 old bug #1835 problem to be dealt with.

 If the EC turns off the power to the SD and then say 200us later the WLAN
 gets a wakeup packet we may violate the power off hold time needed for the
 SD card.

 For all wakeups except WLAN the EC has control over when it issues an SCI
 and could implement a minimum off period before it wakes up the host.
 Thats how we solved #1835 in XO-1.  But on 1.5 WLAN wakeups do not route
 via the EC.

 The EC could still enforce a minimum off time for the SD device but
 depending on how long that period has to be the host may need to be
 prepared to wait until the SD has been allowed to power back up.

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Ticket URL: <http://dev.laptop.org/ticket/9692#comment:3>
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