On 16 December 2011 19:53, Kenneth Graunke <kenn...@whitecape.org> wrote:
> On 12/14/2011 11:59 AM, Paul Berry wrote: > > This patch enables rasterizer discard functionality (a part of > > transform feedback) in Gen6, by generating an alternate GS program > > when rasterizer discard is active. Instead of forwarding vertices > > down the pipeline, the alternate GS program uses a URB Write message > > to deallocate the URB entry that was allocated by FF sync and > > terminate the thread. > > > > Note: parts of the Sandy Bridge PRM seem to imply that we could do > > this more efficiently, by clearing the GEN6_GS_RENDERING_ENABLE bit, > > and not allocating a URB entry at all. However, it's not clear how we > > are supposed to terminate the thread if we do that. Volume 2 part 1, > > section 4.5.4, says "GS threads must terminate by sending a URB_WRITE > > message with the EOT and Complete bits set.", and my experiments so > > far confirm that. > > --- > > > > This patch needs to be applied on top of the series "[PATCH 0/8] i965 > > gen6: Initial implementation of transform feedback.", which is still > > under review on the mailing list. > > Assuming the dirty bit gets sorted out, > Reviewed-by: Kenneth Graunke <kenn...@whitecape.org> > > Thanks, Ken. Fortunately, this patch is independent of the dirty bit stuff (since this patch adds a use of ctx->TransformFeedback.RasterDiscard to brw_gs_prog, which already depends on _NEW_TRANSFORM). So I'll push it as soon as the remaining discussion on my main transform feedback series is resolved.
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