#12110 HIGH 4-softw: XO-4 wallows when using the touchscreen

[Zarro Boogs per Child]

#12110: XO-4 wallows when using the touchscreen
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           Reporter:  wad       |       Owner:  pgf                              
               Type:  defect    |      Status:  new                              
           Priority:  high      |   Milestone:  4-software                       
          Component:  kernel    |     Version:  Development build as of this date
         Resolution:            |    Keywords:  XO-4, touchscreen                
        Next_action:  diagnose  |    Verified:  0                                
Deployment_affected:            |   Blockedby:                                   
           Blocking:            |  
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Comment(by pgf):

 if i do as instructed, then top stops reporting new data because the
 Terminal is constantly selecting/deselecting text.  you can get the same
 sort of "freeze" if you hold down the left button and move your finger
 around on the touchpad.

 however, the touchscreen does consume more cpu than the touchpad.  if you
 instead run top on a serial console, and move your finger around on a
 sugar screen, it's easy to get python and X to take a combined 75% of the
 CPU.

 removing the zforce module, and reloading it with reduced idle and full
 scanning frequencies, as below, cuts the CPU usage of the above scenario
 in half (which is roughly the same CPU usage as when doing the same thing
 with the touchpad).  it remains to be seen what the proper tunings for
 these values is.

 {{{
 bash-4.2# cat /sys/kernel/debug/zforce/settings
 firmware 0.0.0.2
 active 1, touches 0
 scanning 580, prepared 0, sent 0, invalid 0
 config 0x1
 freq: idle 255, full 255, pen 255
 resolution: w 1200 h 900, physical: w 152 h 115
 leds x 0-14 y 0-10
 maxstrength 64
 touch area: en 1 max 31, en 0 min 0
 bash-4.2# modprobe -r zforce
 bash-4.2# modprobe  zforce idlescanfreq=10 fullscanfreq=100
 [ 6584.026005] zforce: running in single touch mode
 [ 6584.030891] input: zForce touchscreen as
 /devices/d4033000.i2c/i2c-5/5-0050/input/input61
 [ 6584.074018] input: olpc-kbdshim virtual touchscreen as
 /devices/virtual/input/input62
 [ 6584.094586] zforce: found zForce firmware 0.0.0.2
 bash-4.2# cat /sys/kernel/debug/zforce/settings
 firmware 0.0.0.2
 active 1, touches 0
 scanning 56, prepared 0, sent 0, invalid 0
 config 0x1
 freq: idle 10, full 100, pen 255
 resolution: w 1200 h 900, physical: w 152 h 115
 leds x 0-14 y 0-10
 maxstrength 64
 touch area: en 1 max 31, en 0 min 0

 }}}

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Ticket URL: <http://dev.laptop.org/ticket/12110#comment:1>
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