Independent clone mode

[Barry Song]

Pekka Paalanen <ppaalanen at gmail.com> 于2019年7月26日周五 上午3:30写道：
>
> On Thu, 25 Jul 2019 13:00:55 +1200
> Barry Song <21cnbao at gmail.com> wrote:
>
> > Pekka Paalanen <ppaalanen at gmail.com> 于2019年7月24日周三 下午8:10写道：
> > >
> > > On Wed, 24 Jul 2019 13:22:43 +0800
> > > zou lan <nancy.lan.zou at gmail.com> wrote:
> > >
> > > > Hi pekka
> > > >
> > > > I see the clone mode is supported from this commit message.
> > > > https://patchwork.freedesktop.org/patch/227970/
> > > >
> > > > I also see the message  "Independent CRTC clone mode cannot be supported
> > > > until output layout logic is moved from libweston into the frontend and
> > > > libweston's damage tracking issues stemming from overlapping outputs are
> > > > solved".
> > > >
> > > > I want to ask is independent CRTC clone mode already supported in Weston  6
> > > > or 7? If not,
> > > > is there a plan to support it?
> > >
> > > Hi,
> > >
> > > no, that commit message is still accurate. I don't know of any
> > > plans to work on independent CRTC clone mode.
> >
> > Pekka,
> > any possible workaround do you know to support independent crtc clone
> > within weston? right now it is very important product feature.
> > for example, force weston to identify only one screen, and sync copy
> > the screen to 2nd screen and call the drm api of 2nd screen?
>
> Hi,
>
> you could hack it up to do that, but it would be in no way an
> upstreamable solution. It would also hurt display timings because
> every repaint would have to wait for both monitors to refresh. Or,
> all but one monitor would tear.
>
> A simpler hack would be to create overlapping outputs and
> force them repaint fully on every refresh instead of repainting
> only the damage. That's not upstreamable either, but the damage
> could be hacked with probably a one-liner.

Hi Pekka,
Thanks. even though i have seen many times that damage tracking of
overlapping outputs is the main cause stopping weston from supporting
full clone mode, i haven't fully understood what is overlapping
outputs in weston and found the code related with overlapping output,
would you like to point out some code path so that i can begin to do
some work on it? pls forgive me if you think the question is just
stupid.

>
>
> Thanks,
> pq

-barry