[Mesa-dev] [PATCH 13/14] vl/dri3: implement functions for get and set timestamp

Axel Davy axel.davy at ens.fr
Wed May 11 21:18:55 UTC 2016

On 11/05/2016 23:08, Leo Liu wrote:
> scrn->next_msc = ((int64_t)stamp - scrn->last_ust + scrn->ns_frame/2) /
> +                       scrn->ns_frame + scrn->last_msc; 

Could you explain this calculation ?

I think it may get issues if ns_frame is wrong. For example for some 
reason (app hidden for some frame, or monitor shut, or whatever), I 
think we could get two buffers getting complete event with same ust (one 
skipped, and one shown).

I think the calculation should be made more robust to issues with 
ns_frame. Perhaps do some temporal averaging of ns_frame and ignore 
outliers ?


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