#12377 LOW 4-firmw: XO-4 B1 timeout entering DCON mode

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#12377: XO-4 B1 timeout entering DCON mode
---------------------------------+------------------------------------------
 Reporter:  Quozl                |                 Owner:  Quozl               
     Type:  defect               |                Status:  new                 
 Priority:  low                  |             Milestone:  4-firmware          
Component:  ofw - open firmware  |               Version:  Development firmware
 Keywords:                       |           Next_action:  reproduce           
 Verified:  0                    |   Deployment_affected:                      
Blockedby:                       |              Blocking:                      
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 A long duration DCON freeze and unfreeze test was set up, consisting of:

 {{{
 dev /display
 : hdd-led-off  led-storage-gpio# gpio-clr  ;
 : hdd-led-on  led-storage-gpio# gpio-set  ;
 : yy  hdd-led-on dcon-freeze hdd-led-off dcon-unfreeze  ;
 : xx  begin yy key? until key drop  ;
 gvsr xx gvsb xx
 }}}

 On XO-4 B1 SKU292 (4b18) with Q7B08.

 About 3900 seconds into the test, a scrolling error began:
 {{{
 Timeout entering DCON mode
 }}}

 Interrupting the test, diagnosis showed:
  * ''get-msecs'' returned 3baf52,
  * ''dcon-freeze'' was generating the error,
  * ''dcon-unfreeze'' was not generating any error,
  * ''has-dcon-ram?'' returned true,
  * brightness keyboard keys continued to work properly,
  * ''mode@'' returned 69 (pass-through disable, backlight enable, color
 swizzling enable, color anti-aliasing enable),
  * ''select /dcon dcon-unload'' or ''dcon-load'' had no effect on screen
 image, it continued to be live,
  * the alternate function register for GPIO 142 was correct (1), and the
 GPIO direction was correct (output), and ''gpio-pin@ 1 and'' tracked
 ''dcon-unload'' (1) and ''dcon-load'' (0),
  * a soft reset of the DCON memory controller was ineffective, (''1 42
 dcon! 1 ms 0 42 dcon! ''),
  * a system power cycle cleared the problem.

 The problem has not reproduced on two other units (SKU293, SKU294).

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Ticket URL: <http://dev.laptop.org/ticket/12377>
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