#8526 HIGH 8.2.0 (: display backlight dims for no good reason

Zarro Boogs per Child bugtracker at laptop.org
Wed Sep 17 15:00:55 EDT 2008


#8526: display backlight dims for no good reason
-----------------------------------+----------------------------------------
   Reporter:  thomaswamm           |       Owner:  cjb                              
       Type:  defect               |      Status:  new                              
   Priority:  high                 |   Milestone:  8.2.0 (was Update.2)             
  Component:  power manager (OHM)  |     Version:  Development build as of this date
 Resolution:                       |    Keywords:  cjbfor8.2                        
Next_action:  diagnose             |    Verified:  0                                
  Blockedby:                       |    Blocking:  8006                             
-----------------------------------+----------------------------------------

Comment(by pgf):

 here's a trace of ohmd during the PowerPlug scenario above.  the comments
 refer to
 what happened _above_ the commen.  (i.e., i annotated the log after
 performing each step.

 trace captured with strace, for no particular reason except when i started
 exploring i didn't want to restart ohmd.  (though i did eventually to
 ensure reproducability.)

 {{{
 bash-3.2# /etc/init.d/ohmd restart
 Stopping Open Hardware Manager: [  OK  ]
 Starting Open Hardware Manager: [  OK  ]
 bash-3.2# strace -p $(pidof ohmd) -e trace=write -e write=2 -s 100
 Process 2027 attached - interrupt to quit

 }}}


 here's the trace:

 {{{


 [ brightness is full up  ]

 write(1, "** (ohmd:2027): DEBUG: hardware_brightness is set to 13.\n", 57)
 = 57
 write(1, "** (ohmd:2027): DEBUG: backlight_set_brightness\n", 48) = 48
 write(9, "13", 2)                       = 2
 write(1, "** (ohmd:2027): DEBUG: in set_dcon_mode, mode is 0\n", 51) = 51
 write(9, "0", 1)                        = 1
 write(1, "** (ohmd:2027): DEBUG: hardware_brightness is set to 11.\n", 57)
 = 57
 write(1, "** (ohmd:2027): DEBUG: backlight_set_brightness\n", 48) = 48
 write(9, "11", 2)                       = 2
 write(1, "** (ohmd:2027): DEBUG: hardware_brightness is set to 9.\n", 56)
 = 56
 write(1, "** (ohmd:2027): DEBUG: backlight_set_brightness\n", 48) = 48
 write(9, "9", 1)                        = 1
 write(1, "** (ohmd:2027): DEBUG: hardware_brightness is set to 7.\n", 56)
 = 56
 write(1, "** (ohmd:2027): DEBUG: backlight_set_brightness\n", 48) = 48
 write(9, "7", 1)                        = 1
 write(1, "** (ohmd:2027): DEBUG: hardware_brightness is set to 5.\n", 56)
 = 56
 write(1, "** (ohmd:2027): DEBUG: backlight_set_brightness\n", 48) = 48
 write(9, "5", 1)                        = 1
 write(1, "** (ohmd:2027): DEBUG: hardware_brightness is set to 3.\n", 56)
 = 56
 write(1, "** (ohmd:2027): DEBUG: backlight_set_brightness\n", 48) = 48
 write(9, "3", 1)                        = 1
 write(1, "** (ohmd:2027): DEBUG: hardware_brightness is set to 1.\n", 56)
 = 56
 write(1, "** (ohmd:2027): DEBUG: backlight_set_brightness\n", 48) = 48
 write(9, "1", 1)                        = 1
 write(1, "** (ohmd:2027): DEBUG: hardware_brightness is set to 0.\n", 56)
 = 56
 write(1, "** (ohmd:2027): DEBUG: backlight_set_brightness\n", 48) = 48
 write(9, "0", 1)                        = 1
 write(1, "** (ohmd:2027): DEBUG: in set_dcon_mode, mode is 1\n", 51) = 51
 write(9, "1", 1)                        = 1

 [ manually reduced brightness to 0 ]

 write(1, "** (ohmd:2027): DEBUG: reset_brightness\n", 40) = 40
 write(1, "** (ohmd:2027): DEBUG: backlight_get_brightness\n", 48) = 48
 write(1, "** (ohmd:2027): DEBUG: Level is 0\n.\n", 36) = 36
 write(1, "** (ohmd:2027): DEBUG: Level is 0.\n", 35) = 35
 write(1, "** (ohmd:2027): DEBUG: Setting value_new to 0, ac: 15, battery:
 15, idle: 6.\n", 77) = 77
 write(1, "** (ohmd:2027): DEBUG: reset_brightness: acadapter.state = 0,
 setting brightness 0\n", 83) = 3

 [ pulled power ]

 write(1, "** (ohmd:2027): DEBUG: reset_brightness\n", 40) = 40
 write(1, "** (ohmd:2027): DEBUG: backlight_get_brightness\n", 48) = 48
 write(1, "** (ohmd:2027): DEBUG: Level is 0\n.\n", 36) = 36
 write(1, "** (ohmd:2027): DEBUG: Level is 0.\n", 35) = 35
 write(1, "** (ohmd:2027): DEBUG: Setting value_new to 0, ac: 15, battery:
 15, idle: 6.\n", 77) = 77
 write(1, "** (ohmd:2027): DEBUG: reset_brightness: acadapter.state = 1,
 setting brightness 0\n", 83) = 3


 [ replaced power ]

 write(1, "** (ohmd:2027): DEBUG: hardware_brightness is set to 2.\n", 56)
 = 56
 write(1, "** (ohmd:2027): DEBUG: backlight_set_brightness\n", 48) = 48
 write(9, "2", 1)                        = 1
 write(1, "** (ohmd:2027): DEBUG: in set_dcon_mode, mode is 0\n", 51) = 51
 write(9, "0", 1)                        = 1
 write(1, "** (ohmd:2027): DEBUG: hardware_brightness is set to 4.\n", 56)
 = 56
 write(1, "** (ohmd:2027): DEBUG: backlight_set_brightness\n", 48) = 48
 write(9, "4", 1)                        = 1
 write(1, "** (ohmd:2027): DEBUG: hardware_brightness is set to 6.\n", 56)
 = 56
 write(1, "** (ohmd:2027): DEBUG: backlight_set_brightness\n", 48) = 48
 write(9, "6", 1)                        = 1
 write(1, "** (ohmd:2027): DEBUG: hardware_brightness is set to 8.\n", 56)
 = 56
 write(1, "** (ohmd:2027): DEBUG: backlight_set_brightness\n", 48) = 48
 write(9, "8", 1)                        = 1
 write(1, "** (ohmd:2027): DEBUG: hardware_brightness is set to 10.\n", 57)
 = 57
 write(1, "** (ohmd:2027): DEBUG: backlight_set_brightness\n", 48) = 48
 write(9, "10", 2)                       = 2
 write(1, "** (ohmd:2027): DEBUG: hardware_brightness is set to 12.\n", 57)
 = 57
 write(1, "** (ohmd:2027): DEBUG: backlight_set_brightness\n", 48) = 48
 write(9, "12", 2)                       = 2
 write(1, "** (ohmd:2027): DEBUG: hardware_brightness is set to 14.\n", 57)
 = 57
 write(1, "** (ohmd:2027): DEBUG: backlight_set_brightness\n", 48) = 48
 write(9, "14", 2)                       = 2
 write(1, "** (ohmd:2027): DEBUG: hardware_brightness is set to 15.\n", 57)
 = 57
 write(1, "** (ohmd:2027): DEBUG: backlight_set_brightness\n", 48) = 48
 write(9, "15", 2)                       = 2

 [ manually increased brightness to full ]

 write(1, "** (ohmd:2027): DEBUG: reset_brightness\n", 40) = 40
 write(1, "** (ohmd:2027): DEBUG: backlight_get_brightness\n", 48) = 48
 write(1, "** (ohmd:2027): DEBUG: Level is 15\n.\n", 37) = 37
 write(1, "** (ohmd:2027): DEBUG: Level is 15.\n", 36) = 36
 write(1, "** (ohmd:2027): DEBUG: value_user (0) isn\'t a default, so
 preserving.\n", 70) = 70
 write(1, "** (ohmd:2027): DEBUG: reset_brightness: acadapter.state = 0,
 setting brightness 0\n", 83) = 3
 write(1, "** (ohmd:2027): DEBUG: hardware_brightness is set to 0.\n", 56)
 = 56
 write(1, "** (ohmd:2027): DEBUG: backlight_set_brightness\n", 48) = 48
 write(9, "0", 1)                        = 1

 [ pulled power -- brightness is now 0 -- (but screen still in color mode)
 ]


 }}}

-- 
Ticket URL: <http://dev.laptop.org/ticket/8526#comment:7>
One Laptop Per Child <http://laptop.org/>
OLPC bug tracking system


More information about the Bugs mailing list