On Thu, 10 May 2018 12:53:49 +0800 zou lan <[email protected]> wrote:
> Hi pekka > > I test presentation on my side. The presentation results is not accurate > because our pageflip event send last frame's timestamp every time. So > weston_output_finish_frame send last frame's present tine > to current frame's feedback. For this situation, I just delay one frame to > send present event. Does this get the right c2p time? Thank you. Hi Nancy, I think your driver needs to get fixed, so that it provides the correct timestamp instead of an outdated one. If this is a kernel DRM driver, then the behaviour you describe is clearly a bug. The timestamp of the pageflip event signifies the time the new frame starts transmitting out of the connector. I believe there should be DRM driver API documentation stating that. This is also what weston_output_finish_frame() expects. Anything else will cause the frame scheduling to misbehave. It may be possible to work around the bug as you suggest, but that will make the compositor incorrect on any other driver, and it may cause other subtle breakage (the timestamp may be correct, but the time the event gets sent is now wrong and might even be delayed indefinitely if nothing causes a repaint). Thanks, pq
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