#9333 BLOC 1.5-F11: screen flicker in X

[Zarro Boogs per Child]

#9333: screen flicker in X
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           Reporter:  dsd              |       Owner:  dsd          
               Type:  defect           |      Status:  new          
           Priority:  blocker          |   Milestone:  1.5-F11      
          Component:  x window system  |     Version:  not specified
         Resolution:                   |    Keywords:               
        Next_action:  diagnose         |    Verified:  0            
Deployment_affected:                   |   Blockedby:               
           Blocking:                   |  
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Comment(by mikus):

 Replying to [comment:17 wmb at firmworks.com]:
 > I suppose the problem might be related to the timing parameters we have
 chosen.  If the timing is marginal with respect to the requirements of the
 DCON+panel hardware, the screen might briefly lose sync in certain cases.
 One such case might be some kinds of redraws that might cause noise to be
 coupled into the timing lines.

 Though I'm not sure of the circumstances that cause this to happen, I've
 seen the Frame (or perhaps the entire screen's content) drawn too small,
 so that it does not extend to the edges of the actual XO screen.
 Thereupon that picture is re-drawn slightly bigger.  If it still does not
 reach the edge, it is redrawn again, etc.  [All this happens in a fraction
 of a second.]  The visual impression conveyed to the human viewer is that
 the system is __unsure__ of where the picture it was told to draw belongs,
 and it is trying by means of multiple iterations to fit that picture into
 place.

 The flickering shows up for me on the XO-1.5 every time the Frame gets
 taken off the screen, or gets put on the screen.  All the Views flicker as
 well, except it is over before I can tell what is happening visually.  I
 have also noticed flicker when some (but not all) updates of the Terminal
 screen are performed.

 [Note:  While I have not particularly noticed flickering with the XO-1,
 there have been occasions back in XO-1 days when something has
 *interrupted* the drawing of the screen -- leaving "shorelines" along some
 edges (as if leftover from trying to put into place pictures of differing
 sizes).]

 Would 'timing parameters' cause the so-called "unsureness" I've seen with
 Frame ?


 --------

 In any case, if you would please tell me what to *zap* in the kernel to
 change the timing parameter values you talk about, I'd be glad to carry
 out experiments to see what effect they have on the flicker.   <mikus at
 bga.com>

-- 
Ticket URL: <http://dev.laptop.org/ticket/9333#comment:18>
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