On 2021-09-06 17:38, Uma Shankar wrote: > This is a RFC proposal for plane color hardware blocks. > It exposes the property interface to userspace and calls > out the details or interfaces created and the intended > purpose. > > Credits: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > Signed-off-by: Uma Shankar <uma.shankar@xxxxxxxxx> > --- > Documentation/gpu/rfc/drm_color_pipeline.rst | 167 +++++++++++++++++++ > 1 file changed, 167 insertions(+) > create mode 100644 Documentation/gpu/rfc/drm_color_pipeline.rst > > diff --git a/Documentation/gpu/rfc/drm_color_pipeline.rst b/Documentation/gpu/rfc/drm_color_pipeline.rst > new file mode 100644 > index 000000000000..0d1ca858783b > --- /dev/null > +++ b/Documentation/gpu/rfc/drm_color_pipeline.rst > @@ -0,0 +1,167 @@ > +================================================== > +Display Color Pipeline: Proposed DRM Properties > +================================================== > + > +This is how a typical display color hardware pipeline looks like: > + +-------------------------------------------+ > + | RAM | > + | +------+ +---------+ +---------+ | > + | | FB 1 | | FB 2 | | FB N | | > + | +------+ +---------+ +---------+ | > + +-------------------------------------------+ > + | Plane Color Hardware Block | > + +--------------------------------------------+ > + | +---v-----+ +---v-------+ +---v------+ | > + | | Plane A | | Plane B | | Plane N | | > + | | DeGamma | | Degamma | | Degamma | | > + | +---+-----+ +---+-------+ +---+------+ | > + | | | | | > + | +---v-----+ +---v-------+ +---v------+ | > + | |Plane A | | Plane B | | Plane N | | > + | |CSC/CTM | | CSC/CTM | | CSC/CTM | | > + | +---+-----+ +----+------+ +----+-----+ | > + | | | | | > + | +---v-----+ +----v------+ +----v-----+ | > + | | Plane A | | Plane B | | Plane N | | > + | | Gamma | | Gamma | | Gamma | | > + | +---+-----+ +----+------+ +----+-----+ | > + | | | | | > + +--------------------------------------------+ > ++------v--------------v---------------v-------| > +|| || > +|| Pipe Blender || > ++--------------------+------------------------+ > +| | | > +| +-----------v----------+ | > +| | Pipe DeGamma | | > +| | | | > +| +-----------+----------+ | > +| | Pipe Color | > +| +-----------v----------+ Hardware | > +| | Pipe CSC/CTM | | > +| | | | > +| +-----------+----------+ | > +| | | > +| +-----------v----------+ | > +| | Pipe Gamma | | > +| | | | > +| +-----------+----------+ | > +| | | > ++---------------------------------------------+ > + | > + v > + Pipe Output > + This diagram defines what happens before and after the blending space but did where does scaling fit into it? Scaling can look different when performed in linear or non-linear space so I think it is important to define where in the pipeline it sits. In my view scaling would happen between plane degamma and plane CSC. Harry > +Proposal is to have below properties for a plane: > + > +* Plane Degamma or Pre-Curve: > + * This will be used to linearize the input framebuffer data. > + * It will apply the reverse of the color transfer function. > + * It can be a degamma curve or OETF for HDR. > + * This linear data can be further acted on by the following > + * color hardware blocks in the display hardware pipeline > + > +UAPI Name: PLANE_DEGAMMA_MODE > +Description: Enum property with values as blob_id's which advertizes the > + possible degamma modes and lut ranges supported by the platform. > + This allows userspace to query and get the plane degamma color > + caps and choose the appropriate degamma mode and create lut values > + accordingly. > + > +UAPI Name: PLANE_DEGAMMA_LUT > +Description: Blob property which allows a userspace to provide LUT values > + to apply degamma curve using the h/w plane degamma processing > + engine, thereby making the content as linear for further color > + processing. Userspace gets the size of LUT and precision etc > + from PLANE_DEGAMA_MODE_PROPERTY > + > +* Plane CTM > + * This is a Property to program the color transformation matrix. > + * This can be used to perform a color space conversion like > + * BT2020 to BT709 or BT601 etc. > + * This block is generally kept after the degamma unit so that > + * linear data can be fed to it for conversion. > + > +UAPI Name: PLANE_CTM > +Description: Blob property which allows a userspace to provide CTM coefficients > + to do color space conversion or any other enhancement by doing a > + matrix multiplication using the h/w CTM processing engine > + > +* Plane Gamma or Post-Curve > + * This can be used to perform 2 operations: > + * non-lineralize the framebuffer data. Can be used for > + * non linear blending. It can be a gamma curve or EOTF > + * for HDR. > + * Perform Tone Mapping operation. This is an operation > + * done when blending is done with HDR and SDR content. > + > +UAPI Name: PLANE_GAMMA_MODE > +Description: Enum property with values as blob_id's which advertizes the > + possible gamma modes and lut ranges supported by the platform. > + This allows userspace to query and get the plane gamma color > + caps and choose the appropriate gamma mode and create lut values > + accordingly. > + > +UAPI Name: PLANE_GAMMA_LUT > +Description: Blob property which allows a userspace to provide LUT values > + to apply gamma curve or perform tone mapping using the h/w plane > + gamma processing engine, thereby making the content as linear > + for further color processing. Userspace gets the size of LUT and > + precision etc from PLANE_GAMA_MODE_PROPERTY > + > +This is part of one plane engine. Data from multiple planes will be > +then fed to pipe where it will get blended. There is a similar set of > +properties available at crtc level which acts on this blended data. > + > +Below is a sample usecase: > + > + ┌────────────┐ ┌─────────────┐ ┌─────────────┐ ┌─────────────┐ > + │FB1 │ │Degamma Block│ │ CTM Matrix │ │ Gamma Block │ > + │ ├─────►│Linearize- ├────►│ BT709 to ├────►│ SDR to HDR │ > + │BT709 SDR │ │BT709 inverse│ │ BT2020 │ │ Tone Mapping├────────┐ > + └────────────┘ └─────────────┘ └─────────────┘ └─────────────┘ │ > + │ > + ┌────────────┐ ┌─────────────┐ ┌─────────────┐ ┌─────────────┐ │ > + │FB2 │ │Degamma Block│ │ CTM Matrix │ │ Gamma Block │ │ > + │ ├─────►│Linearize- ├────►│ BT601 to ├────►│ SDR to HDR ├─────┐ │ > + │BT601 SDR │ │BT601 inverse│ │ BT2020 │ │ Tone Mapping│ │ │ > + └────────────┘ └─────────────┘ └─────────────┘ └─────────────┘ │ │ > + │ │ > + ┌────────────┐ ┌─────────────┐ ┌─────────────┐ ┌─────────────┐ │ │ > + │FB3 │ │Degamma Block│ │ CTM Matrix │ │ Gamma Block │ │ │ > + │ ├─────►│Linearize- ├────►│ NOP (Data in├────►│ NOP (Data in├───┐ │ │ > + │BT2020 HDR │ │HDR OETF │ │ BT2020) │ │ HDR) │ │ │ │ > + └────────────┘ └─────────────┘ └─────────────┘ └─────────────┘ │ │ │ > + │ │ │ > + │ │ │ > + │ │ │ > +┌───────────────────────────────────────────────────────────────────────────────┴─┴──┘ > +│ > +│ ┌─────────────┐ ┌─────────────┐ ┌───────────────┐ > +│ │ CRTC Degamma│ │ CRTC CTM │ │ CRTC Gamma │ > +└─┤ Use to make ├─────►│ Use for any ├─────►│ Use for Tone ├─────► TO Port > + │ data linear │ │ Color Space │ │ Mapping/apply │ > + │ after blend │ │ Conversion │ │ transfer func │ > + └─────────────┘ └─────────────┘ └───────────────┘ > + > + > +This patch series adds properties for plane color features. It adds > +properties for degamma used to linearize data and CSC used for gamut > +conversion. It also includes Gamma support used to again non-linearize > +data as per panel supported color space. These can be utilize by user > +space to convert planes from one format to another, one color space to > +another etc. > + > +Userspace can take smart blending decisions and utilize these hardware > +supported plane color features to get accurate color profile. The same > +can help in consistent color quality from source to panel taking > +advantage of advanced color features in hardware. > + > +These patches add the property interfaces and enable helper functions. > +This series adds Intel's XE_LPD hw specific plane gamma feature. We > +can build up and add other platform/hardware specific implementation > +on top of this series. > + > +Credits: Special mention and credits to Ville Syrjala for coming up > +with a design for this feature and inputs. This series is based on > +his original design and idea. >
