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[directfb-dev] Re: Flipping troubles - videolayer, crtc2
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[directfb-dev] Re: Flipping troubles - videolayer, crtc2



On Wed, 2002-06-19 at 02:22, Jiří Svoboda wrote:
> Hi,
> 
> > On Tue, 2002-06-18 at 16:58, Jiri Svoboda wrote:
> > > Hi,
> > > 
> > > > Thanks.  I've tested it but I get only a green screen
> > > > (symptom of backbuffer not being flipped at all).
> > > 
> > > Will check it.
> Is Your driver creating flipping surface as default? Even if not
> specified/layer not configured?
> 
Yes, the default buffermode is DLBM_BACKVIDEO.  So, it will create a
flipping layer unless otherwise specified, ie, by doing a
SetConfiguration with buffermode as DLBM_FRONTONLY.
   
> > >  
> > > > I think it's because when you test for the YV12 blit, and it is 
> > > > true,
> > > > you set do_flipping=0.  I think buggy YV12 blitting and 
> > > > buffer flipping are two separate issues, and should be tested 
> > > > separately.
> > > 
> > > I set do_flipping on version basis - for 0.9.12 and above (same as 
> > > blit). And it is connected to YV12 blit. If I set backbuffer into 
> > > system memory flipping works only when bitblt is OK. So I enabled 
> > > flipping for version 0.9.12 and above. BTW: flipping on 
> > matrox BES is 
> > > supoorted also from 0.9.12....
> > > 
> > > Because of bitblt bug flipping is not safe on 0.9.11 even if it is 
> > > supported by dfb.
> > 
> > Flipping from backvideo should not be affected by the blit 
> > bug, only flipping from the backsystem.  I guess you can use 
> > a test similar to the
> > following:
> > 
> > create/get DLBM_BACKVIDEO layer, then test for flipping 
> > support by issuing a layer->Flip.  
> 
> I did not test it yet, but I think this will not work. Flip will be OK
> in all case, but nothing displayed for DLBM_BACKSYSTEM.
> I will solve this by disabling DLBM_BACKSYSTEM for dfb 0.9.11.
> 
> JS
> 
Not necessarily.  Flipping has to be supported by the low level driver
itself.  For instance, although 0.9.11 will support a flipping surface, 
the gfxdrivers xxxFlipBuffers() may return DFB_UNIMPLEMENTED. Versions
older than 0.9.11 will not support flipping nor flipping surfaces at
all.  So, a prelimary layer->Flip call may tell you if flipping will
actually be supported even if a flipping surface was successfully
created.

Tony




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