[meta-freescale] Any hope of vblank-synchronized rendering (from vivante) on i.MX6 soon?

[Prabhu S]

On Tue, Sep 23, 2014 at 1:46 PM, Eric Nelson <
eric.nelson at boundarydevices.com> wrote:

> Hi Carlos,
>
> On 09/23/2014 10:52 AM, Carlos Rafael Giani wrote:
> >
> > I wonder why it is single buffered. is it because of the memory
> > consumption for a second buffer? The buffers could be flipped,
> > eliminating any need for blits, so the memory bandwidth should not be an
> > issue.
> >
>
> There is a memory bandwidth implication.
>
> Assuming frame buffers A and B in a double-buffered system,
> rendering will occur into B while A is displayed, then the
> two will be swapped, such that B is displayed and A is the
> new rendering output.
>
> In order for apps to only update parts of their windows, any
> "dirty" blocks need to be copied from B to A in the process
> of the flip.
>
> > On 2014-09-23 18:48, Prabhu S wrote:
> >> i.MX6 X11 EGL is single buffered and there is no support for VSYNC.
> >> The tearing with X11 is a known issue. We did investigate to fix this,
> >> but the solution becomes too hacky and cannot be used in production
> >> systems.
> >>
> >> We are adding VSYNC support in Wayland. eglSwapInterval will be
> >> supported for FBDEV and Wayland backends in the upcoming release(in
> >> january). So Ozone-wayland can take advantage of this.
> >>
>
> ?? This is already supported in Wayland, though it is controlled
> by an environment variable.
>
export FB_MULTI_BUFFER=2. By doing this server side is VYSNC controlled.
The client side support in next release.

>
> You can see it in action by watching /sys/class/graphics/fb0/pan.
>
> Regards,
>
>
> Eric
>
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