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The V3D documentation states that primitive counters are reset when we emit Tile Binning Mode Configuration items, which we do at the start of each draw call, however, in the actual hardware this doesn't seem to take effect when transform feedback is not active (this doesn't happen in the simulator). This causes a problem in the following scenario: glBeginTransformFeedback() glDrawArrays() glPauseTransformFeedback() glDrawArrays() glResumeTransformFeedback() glEndTransformFeedback() The TF pause will trigger a flush of the primitive counters, which results in a correct number of primitives up to that point. In theory, the counter should then be reset when we execute the draw after pausing TF, but that doesn't happen, and since TF is enabled again by the resume command before we end recording, by the time we end the transform feedback recording we again check the counters, but instead of reading 0, we read again the same value we read at the time we paused, incorrectly accumulating that value again. In theory, we should be able to avoid this by using the other method to reset the primitive counters: using operation 1 instead of 0 when we flush the counts to the buffer at the time we pause, but again, this doesn't seem to be work and we still see obsolete counts by the time we end transform feedback. This patch fixes the problem by not accumulating TF primitive counts unless we know we have actually queued draw calls during transform feedback, since that seems to effectively reset the counters. This should also be more performant, since it saves unnecessary stalls for the primitive counters to be updated when we know there haven't been any new primitives drawn. Fixes CTS tests: dEQP-GLES3.functional.transform_feedback.* Reviewed-by: Eric Anholt <eric@anholt.net>
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