Re: [PATCH 00/11] Plane Color Pipeline support for MediaTek

["Nícolas F. R. A. Prado" <nfraprado@collabora.com>]

On Fri, 2026-02-06 at 11:09 +0200, Pekka Paalanen wrote:
> On Fri, 2 Jan 2026 13:40:21 -0500
> Harry Wentland <harry.wentland@amd.com> wrote:
> 
> > On 2026-01-01 07:37, Shengyu Qu wrote:
> > > 
> > > 
> > > 在 2025/12/30 02:53, Shengyu Qu 写道:  
> > > > 
> > > > 
> > > > 在 2025/12/24 3:44, NÃ colas F. R. A. Prado 写道:  
> 
> > > > > Given the lack of support for writeback connectors on the
> > > > > MediaTek KMS driver, combined with limited hardware
> > > > > documentation, I haven't been able to verify the correctness
> > > > > of
> > > > > each curve, only that they were visually sane (gamma curves
> > > > > made
> > > > > the image on the display brighter, while inverse gamma made
> > > > > it
> > > > > darker).  
> > > > 
> > > > Hmmm I don't think this is acceptable. sRGB/scRGB has two
> > > > transfer
> > > > functions mentioned in original specification[1]. To keep color
> > > > accuracy, we need someone from mediatek confirm whether this is
> > > > piece- wise or pure power 2.2 transfer function, this is
> > > > already
> > > > done in original amdgpu color pipeline series, sRGB means
> > > > piece-wise while also dedicated power 2.2 function exists.  
> > 
> > Not sure what you mean with this not being acceptable. This is
> > about
> > enabling HW support for this functionality. Not every HW has
> > writeback for testing. At some point you'll have to trust the
> > driver
> > devs if you're going to use functionality of the driver. We're not
> > always going to get everything perfect, but if that's really such a
> > worry you can always use shaders to do precisely what you want.
> > 
> 
> Hi Harry,
> 
> yes, but I understood that in this case, the hardware documentation
> available is so vague that it's impossible to say what it will
> actually
> do. There are no formulas given or referenced in the documentation,
> are
> there, Nícolas?

No formulas at all, the only documentation I had available for the
curves was the register definition, which simply lists the possible
values: SCRGB, BT709, BT2020, HLG.

-- 
Thanks,

Nícolas