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

[Carlos Rafael Giani]

Done. See https://bugzilla.yoctoproject.org/show_bug.cgi?id=6760

On 2014-09-24 17:36, Daiane Angolini wrote:
> On Tue, Sep 23, 2014 at 5:09 PM, Carlos Rafael Giani
> <dv at pseudoterminal.org> wrote:
>> While this is correct for output that is drawn directly to the framebuffer
>> (with damage regions etc.), it isn't for compositor-based output, such as
>> what Weston does. There, it is not uncommon to repaint  the entire screen.
>> If it uses GLES as the backend, this is the only way to do it, unless some
>> extension for swapping buffer subregions exists. Perhaps by using a
>> compositor in X buffer flipping would be viable.
> Carlos, would you mind to open a bug on bugzilla for this VSYNC issue?
>
> It looks like you can describe it better than me. Please add the html
> file you shared and the DISTRO_FEATURES needed to reproduce the issue.
>
> Also, please, say which kernel version you used and which GPU version.
>
> I can then, update this with the comments from Prabhu, and change its
> status accordingly.
>
> Thanks in advance,
> Daiane
>
>>
>> On 2014-09-23 20:46, Eric Nelson 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.
>>>
>>> You can see it in action by watching /sys/class/graphics/fb0/pan.
>>>
>>> Regards,
>>>
>>>
>>> Eric
>>
>> --
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