Ticket #1710 (new defect)

Opened 11 years ago

Last modified 11 years ago

Tearing (Vertical Sync)

Reported by: Mercury Owned by: openmoko-kernel
Priority: low Milestone:
Component: kernel Version:
Severity: major Keywords: vsync vblank sync tearing
Cc: Blocked By:
Blocking: Estimated Completion (week):
HasPatchForReview: PatchReviewResult:


I've noticed a lot of screen tearing, especially in the bootsplash (before and after X starts). I think syncing to vblank should be implemented wherever feasible.

Change History

comment:1 Changed 11 years ago 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.

comment:2 Changed 11 years ago by Mercury

  • Priority changed from highest to low
  • Severity changed from normal to major

That is awful!

I guess this ticket should be left open to track that as a goal. I'm not sure what priority we would want to put on it. In my opinion, it needs to be done in order to be an acceptable multimedia device and to appear polished in general, but it's not breaking anything.

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