#12216 NORM 13.1.0: arm doesn't support 1.8 volt card

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#12216: arm doesn't support 1.8 volt card
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           Reporter:  jvonau     |       Owner:  cjb                     
               Type:  defect     |      Status:  assigned                
           Priority:  normal     |   Milestone:  13.1.0                  
          Component:  kernel     |     Version:  Software Build 12.1.0-21
         Resolution:             |    Keywords:                          
        Next_action:  never set  |    Verified:  0                       
Deployment_affected:             |   Blockedby:                          
           Blocking:             |  
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Changes (by dsd):

 * cc: dsd (added)


Comment:

 The conclusions from the upstream discussion so far is that we haven't
 found a reliable way of power-cycling the SD card on XO-1.75. So we were
 tipping towards adding a quirk.

 Then cjb pointed out this code in the xo-1.75 board file:
 {{{
         gpio_request(35, "ext_sd power");
         gpio_direction_output(35, 1);
         pxa_register_device(&mmp2_device_sdh0, &olpc_xo_1_75_ext_sd,
 sizeof(olpc_xo_1_75_ext_sd));
 }}}

 So I tried implementing a vmmc regulator on gpio 35, spent more time
 fiddling, and didn't get anywhere. In fact, it was as if playing with the
 gpio has no influence at all.

 Sure enough, going back to arm-3.0 and modifying the above board file,
 setting the value to 0 instead of 1, or removing the gpio assignment
 altogether, doesn't stop the external SD card from working (testing with a
 normal 3.3V card as a baseline here).

 When people are back from XO-4 bringup we should do a bit more
 investigation here; is GPIO 35 really hooked up to external SD card power?
 Then we can decide where to go.

-- 
Ticket URL: <http://dev.laptop.org/ticket/12216#comment:6>
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