unique id for wayland objects

zou lan nancy.lan.zou at gmail.com
Thu May 31 03:32:40 UTC 2018

Hi Michel & pekka

>>Yes, drm_handle_vblank must be called before drm_crtc_send_vblank_event,
>>otherwise it's not surprising that the timestamp in the event is wrong. :)
Yes. our code call drm_crtc_send_vblank event first. The orignal fps is 60,
but if I swap the order of drm_crtc_send_vblank_event and
drm_handle_vblank, the fps drop to 30fps.

>>Weston schedules a repaint based on the pageflip timestamp. If the
>>timestamp is in the past by a whole refresh period, the computed new
>>deadline will be in the past as well, so Weston will attempt to repaint
>>as soon as possible.
I agree with this.

>>The intended behaviour is that Weston repaints at most once for each
>>display refresh cycle, the deadline being 7 ms (if using the default
>>value of repaint-window) before the next vblank. In other words, there
>>should be a significant delay (say, 50-90% of a refresh period) between
>>receiving the pageflip event and repaint.
I can't understand this. I use weston 1.9 now, the repaint_msc is 7ms.
our code always execute output_repaint_timer_handler() as soon as possible
because msec always lower than 1ms. Why there is delay?

Best Regards

2018-05-31 0:12 GMT+08:00 Michel Dänzer <michel at daenzer.net>:

> On 2018-05-30 02:48 PM, Pekka Paalanen wrote:
> > On Wed, 30 May 2018 18:33:40 +0800
> > zou lan <nancy.lan.zou at gmail.com> wrote:
> >
> >> Hi pekka
> >>
> >> I'm not familiar with kernel. I know part of drm driver is implement by
> >> ourself. I check the vblank callback function, it sends pageflip event
> >> first if there is a frame complete, update vblank timestamp later.
> >>
> >> I don't know why the owner write code like this. but if I swap the code
> >> order, the fps  decrease a lot.
> >
> > Hi Nancy,
> >
> > I do not know your hardware, so I cannot say why fps decreases, but the
> > order of sending event first and updating the timestamp later does
> > sound wrong to me.
> Yes, drm_handle_vblank must be called before drm_crtc_send_vblank_event,
> otherwise it's not surprising that the timestamp in the event is wrong. :)
> --
> Earthling Michel Dänzer               |               http://www.amd.com
> Libre software enthusiast             |             Mesa and X developer
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