Openmoko Bug #1710: Tearing (Vertical Sync)

Openmoko Public Trac bugs at
Fri Aug 1 07:46:08 CEST 2008

#1710: Tearing (Vertical Sync)
 Reporter:  Mercury                    |        Owner:  openmoko-kernel
     Type:  defect                     |       Status:  new            
 Priority:  highest                    |    Milestone:                 
Component:  System Software            |      Version:                 
 Severity:  normal                     |   Resolution:                 
 Keywords:  vsync vblank sync tearing  |     Blocking:                 
Blockedby:                             |  

Comment(by andy):

 Glamo doesn't have a VSYNC interrupt, I had to ask them directly because I
 couldn't believe it.

 What it does have is some double buffering flipping which is tied to
 VSYNC, but I don't think it matches X AFAIK (but I know next to nothing
 about X).

 The other trick that's possible is it has a "line counter" register that
 says which line it is issuing.  One could use a timer to track this,
 reading it in the timer ISR and the precomputing the time represented by
 the remaining lines and setting the next interrupt for then, this would
 give you a kind of vsync action.

 If nobody implements those, you're stuck with tearing.

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