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Display Rotation problem

Vladimir Zatulovsky
Prodigy 50 points 
We use OMAP3503 processor, WinCE 6.0
  LCD Parallel Interface in Bypass Mode
      

1) This problem happens with high-resolution (800x480) display.
   Display with lower (480x272) resolution has no rotation problems.

2) Screen glitch/flickering occurs when rotating and when screen redrawing.

   Important to note, that static picture is OK, in any angle, even 90 and 270 degrees.
   But, if screen in portrait (90 or 270 degrees) mode, glitch/flickering
   occurs every time when screen redrawing (fully or partly).

   In these cases, always occurs GFXFIFOUNDERFLOW interupt and SYNC LOST 
   occurs too, but not in each redrawing.

3) The similar issue (SDOCM00069806) described in "AM35x-OMAP35x-PSP 03.00.01.06 Release Notes".
   Does it mean both DMA and VRFB based roation?
 
   
  Anybody knows about this problem?

 Thanks in advance

 Michael
  • 0
    TI__Guru*** 125430 points

    I've seen issues like this when people attempted to do rotation using indexing in DISPC. Using VRFB instead resolved the issue.  Rotation will kill your DDR bandwidth if you're not using VRFB.

  • 0
    TI__Mastermind 43875 points

    Michael,

    This type of error occurs if you are using rotation, but not enabling the VRFB.

    If you are using rotation please make sure that you use VRFB.

    Basically, if rotation is used but not VRFB then every single pixel read will cause a page break in memory, hence devastate efficiency. This is why it works with the smaller displays, and seems to be OK as long as you do very little else in the system.

     

    BR,

    Steve