[maemo-developers] SDL, tearing, X overhead and direct framebuffer gfx

[From: Tapani Pälli]

Hello;

ext Siarhei Siamashka wrote:
> On Feb 18, 2008 1:28 PM, Tapani Pälli <tapani.palli at nokia.com> wrote:
>   
>>> Could you please verify and confirm this information? Framebuffer
>>> driver from OS2007 supported tearsync (via OMAPFB_FORMAT_FLAG_TEARSYNC
>>> flag as Frantisek mentioned), and it was used at least for video.
>>> Well, I have noticed some tearing in mplayer with OS2008 though.
>>>
>>>       
>> This is what I've heard from our kernel team members, maybe they could
>> share some more light to this. AFAIK the hardware itself does not offer
>> sync.
>>     
>
> Is it possible to invite kernel team members to join this discussion?
> :) At least it would be nice if they had a look at this thread.
>
>   
They should be reading this :-)

> N800 hardware definitely supports tearsync. It worked fine in OS2007
> (I'm not telling that OS2008 does not support it anymore, I just can't
> check this till I get home). When I looked through xserver sources
> last time, tearsync was used for video planes, but was disabled for
> normal rgb updates. This can be easily explained. Video usually has
>   
OK, maybe this is the reason, I was not familiar with such setting.
Fortunately tearing does not really matter with individual small rects.
When implementing animation with large elements, you will see tearing
though :/

> lower resolution than 800x480, requires less graphics bandwidth and it
> is possible to display it with perfect tearsync. With tearsync enabled
> for rgb updates, we get an ugly tearing line at a fixed location in
> the bottom of screen when doing 800x480 rgb update (the first OS2008
> firmware had this problem btw). Without tearsync flag set, we also get
> tearing, but at random locations on screen, and it is less
> noticeable/annoying.
>   


// Tapani Pälli

-- 
Software Engineer
Open Source Software Operations