YUV support

YUV support

[Dennis Munsie]

Hi again,

I'm starting to investigate adding YUV support to the intelfb driver,  
and I was wondering what support is already in the framebuffer  
subsystem for YUV.  Doing a quick grep for YUV only yielded a handful  
of references -- all in drivers.  Nothing seems to be there for  
generic YUV support.

Am I correct in this assumption?  And, if so, what would be the best  
way to expose YUV support?  Driver specific ioctl's?  Separate fb  
device for the YUV overlay?  Give up and use X? (just kidding on that  
last one -- I hope).

dennis


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Re: YUV support

[Antonino A. Daplas]

Dennis Munsie wrote:
> Hi again,
> 
> I'm starting to investigate adding YUV support to the intelfb driver,  
> and I was wondering what support is already in the framebuffer  
> subsystem for YUV.  Doing a quick grep for YUV only yielded a handful  
> of references -- all in drivers.  Nothing seems to be there for  
> generic YUV support.
> 
> Am I correct in this assumption?

Yes, you are correct.

> And, if so, what would be the best  
> way to expose YUV support?

Create a new visual, FB_VISUAL_YUV_PACKED, then treat 
var->{red,green,blue} as Y, U and V instead. This way, one can continue
to use the cfb_* generic drawing funtions.

For planar formats, it's pretty much the same except you have to provide
your own drawing functions.

> Driver specific ioctl's?

sysfs is probably better.

> Separate fb  
> device for the YUV overlay?

Yes. Some drivers have fb0 for the primary, fb1 for the overlay, and fb2 for
the cursor.

>  Give up and use X?

Or you can use directfb, I bet the i830 there has overlay support.

Tony

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