[PATCH RFC 3/6] drm: Plane YCbCr to RGB conversion related properties

Jyri Sarha jsarha at ti.com
Wed Apr 26 12:56:54 UTC 2017

On 04/24/17 19:55, Ville Syrjälä wrote:
>> In fact we have plane specific YCbCr to RGB CSC (only preoffset
>> possible), then (per crtc) gamma table, and finally a (per crtc) RGB to
>> YCbCr CSC with optional post offset (so it can be used either as CSC or
>> CTM).
> So with that plane hw you could perhaps do:
> - YCbCr->RGB if you input is not linear, but then you must
>   blend using non-linear data
> - colorspace conversion if your input is alredy linear
> And with your crtc hw you could do:
> - degamma + CTM
> - gamma + RGB->YCbCr

Just a generic question. Shouldn't - in an ideal HW - the degamma phase
and the CTM be a plane specific property?

I mean, isn't the purpose of normalizing the non linear RGB to linear
(and possibly converting the color space) to have same format for all
plane data before blending and composing them together?

Of course it does not matter if all the planes use the same color space,
which then should be converted to something else for the output.

... or have I misunderstood something?


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