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 + +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. -- 2.26.2
