[Intel-gfx] [PATCH] i915: add page flipping ioctl

Jesse Barnes jbarnes at virtuousgeek.org
Fri Feb 20 01:43:54 CET 2009

On Thursday 19 February 2009 11:37:01 Chris Wilson wrote:
> With a few additional suggestions by Jesse, I've managed to get
> tear-free compositing working on i915. Here's the diff on top of the
> original patch (though obviously this is just a suggestion, still need
> to prevent multiple pending flips to the same plane and ensure that the
> old buffer is eventually unpinned, and you might choose to drop the
> mutex around the wait_for_vblank ;-):

Yeah, looks pretty reasonable.  Here's what I've been working with.  It adds a 
couple of more changes (and slightly different cleanups) over your version:
  - added a seqno to wait for
  - wait for flip before queuing another
but it's missing thew 915 changes you added (btw did I get the pitch wrong?  
or are you submitting a different value for your objects?).

I added a new seqno since it's possible (even likely) that the next vblank 
won't actually reflect the flip, if the GPU is busy processing a large 
batchbuffer when the ring command goes in for example.

Also it might be a good idea to wait for any previous flip before queuing a 
new one.  Anyway still tracking down some issues with the X side, but it seems 
like it's approaching readiness.

Jesse Barnes, Intel Open Source Technology Center

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