[Trac #1178] Display artifacts when resuming

[Zarro Boogs per Child]

#1178: Display artifacts when resuming
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 Reporter:  wmb at firmworks.com  |       Owner:  mlj      
     Type:  defect             |      Status:  new      
 Priority:  normal             |   Milestone:  Untriaged
Component:  display            |    Keywords:           
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 I now have firmware that does a pretty good job of synchronizing the
 vertical retrace when resuming after a suspend, so that the display does
 not glitch (i.e. no flashing or  jumping).

 But there is still a color artifact that is visible under certain
 conditions.  It is evident when there is an area filled with certain solid
 colors.  The visual appearance is as if the colored area suddenly shows
 narrow (single pixel) diagonal stripes.  It lasts only briefly, perhaps a
 frame or two.

 The effect is more pronounced with partial intensity green and yellow; it
 is difficult to see with blue or with any full-intensity color.

 The effect is very similar to what you see if you move your eyes while
 staring at a colored area of the screen.  In isolation, the effect is
 fairly subtle, but it might become a problem if we do fine-grained
 suspend/resume, thus causing several repetitions per second.

 To demonstrate it, follow this procedure:

 a) Install this firmware image:  http://dev.laptop.org/~wmb/suspend5.rom
 b) Interrupt booting to get to the ok prompt.
 c) ok  screen-ih iselect
 d) ok 0400  0 0   400 300  fill-rectangle
 e) ok s3
 f) Press the power button and observe the green area.

 Another color that shows the effect well is c400 (instead of 0400).

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Ticket URL: <http://dev.laptop.org/ticket/1178>
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