RE: [RFC v2 03/22] drm: Add Plane Degamma Mode property
> -Original Message-
> From: Pekka Paalanen
> Sent: Tuesday, October 12, 2021 5:20 PM
> To: Shankar, Uma
> Cc: intel-...@lists.freedesktop.org; dri-devel@lists.freedesktop.org;
> harry.wentl...@amd.com; ville.syrj...@linux.intel.com; brian.star...@arm.com;
> sebast...@sebastianwick.net; shashank.sha...@amd.com
> Subject: Re: [RFC v2 03/22] drm: Add Plane Degamma Mode property
>
> On Tue, 7 Sep 2021 03:08:45 +0530
> Uma Shankar wrote:
>
> > Add Plane Degamma Mode as an enum property. Create a helper function
> > for all plane color management features.
> >
> > This is an enum property with values as blob_id's and exposes the
> > various gamma modes supported and the lut ranges. Getting the blob id
> > in userspace, user can get the mode supported and also the range of
> > gamma mode supported with number of lut coefficients. It can then set
> > one of the modes using this enum property.
> >
> > Lut values will be sent through separate GAMMA_LUT blob property.
> >
> > Signed-off-by: Uma Shankar
> > ---
> > Documentation/gpu/drm-kms.rst | 90 ++
> > drivers/gpu/drm/drm_atomic.c | 1 +
> > drivers/gpu/drm/drm_atomic_state_helper.c | 2 +
> > drivers/gpu/drm/drm_atomic_uapi.c | 4 +
> > drivers/gpu/drm/drm_color_mgmt.c | 93 ++-
> > include/drm/drm_mode_object.h | 2 +-
> > include/drm/drm_plane.h | 23 ++
> > 7 files changed, 212 insertions(+), 3 deletions(-)
> >
> > diff --git a/Documentation/gpu/drm-kms.rst
> > b/Documentation/gpu/drm-kms.rst index 1ef7951ded5e..f4658417bf20
> > 100644
> > --- a/Documentation/gpu/drm-kms.rst
> > +++ b/Documentation/gpu/drm-kms.rst
> > @@ -545,9 +545,99 @@ Damage Tracking Properties Color Management
> > Properties
> > ---
> >
> > +Below is how a typical hardware pipeline for color will look like:
> > +
> > +.. kernel-render:: DOT
> > + :alt: Display Color Pipeline
> > + :caption: Display Color Pipeline Overview
> > +
> > + digraph "KMS" {
> > + node [shape=box]
> > +
> > + subgraph cluster_static {
> > + style=dashed
> > + label="Display Color Hardware Blocks"
> > +
> > + node [bgcolor=grey style=filled]
> > + "Plane Degamma A" -> "Plane CSC/CTM A"
> > + "Plane CSC/CTM A" -> "Plane Gamma A"
> > + "Pipe Blender" [color=lightblue,style=filled, width=5.25,
> > height=0.75];
> > + "Plane Gamma A" -> "Pipe Blender"
> > + "Pipe Blender" -> "Pipe DeGamma"
> > + "Pipe DeGamma" -> "Pipe CSC/CTM"
> > + "Pipe CSC/CTM" -> "Pipe Gamma"
> > + "Pipe Gamma" -> "Pipe Output"
> > + }
> > +
> > + subgraph cluster_static {
> > + style=dashed
> > +
> > + node [shape=box]
> > + "Plane Degamma B" -> "Plane CSC/CTM B"
> > + "Plane CSC/CTM B" -> "Plane Gamma B"
> > + "Plane Gamma B" -> "Pipe Blender"
> > + }
> > +
> > + subgraph cluster_static {
> > + style=dashed
> > +
> > + node [shape=box]
> > + "Plane Degamma C" -> "Plane CSC/CTM C"
> > + "Plane CSC/CTM C" -> "Plane Gamma C"
> > + "Plane Gamma C" -> "Pipe Blender"
> > + }
> > +
> > + subgraph cluster_fb {
> > + style=dashed
> > + label="RAM"
> > +
> > + node [shape=box width=1.7 height=0.2]
> > +
> > + "FB 1" -> "Plane Degamma A"
> > + "FB 2" -> "Plane Degamma B"
> > + "FB 3" -> "Plane Degamma C"
> > + }
> > + }
> > +
> > +In real world usecases,
> > +
> > +1. Plane Degamma can be used to linearize a non linear gamma encoded
> > +framebuffer. This is needed to do any linear math like color space
> > +conversion. For ex, linearize frames encoded in SRGB or by HDR curve.
>
> Hi,
>
> Maybe better to avoid the term "gamma" as the curves are not always a pure
> power
>
Re: [RFC v2 03/22] drm: Add Plane Degamma Mode property
On Tue, 7 Sep 2021 03:08:45 +0530
Uma Shankar wrote:
> Add Plane Degamma Mode as an enum property. Create a helper
> function for all plane color management features.
>
> This is an enum property with values as blob_id's and exposes
> the various gamma modes supported and the lut ranges. Getting
> the blob id in userspace, user can get the mode supported and
> also the range of gamma mode supported with number of lut
> coefficients. It can then set one of the modes using this
> enum property.
>
> Lut values will be sent through separate GAMMA_LUT blob property.
>
> Signed-off-by: Uma Shankar
> ---
> Documentation/gpu/drm-kms.rst | 90 ++
> drivers/gpu/drm/drm_atomic.c | 1 +
> drivers/gpu/drm/drm_atomic_state_helper.c | 2 +
> drivers/gpu/drm/drm_atomic_uapi.c | 4 +
> drivers/gpu/drm/drm_color_mgmt.c | 93 ++-
> include/drm/drm_mode_object.h | 2 +-
> include/drm/drm_plane.h | 23 ++
> 7 files changed, 212 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/gpu/drm-kms.rst b/Documentation/gpu/drm-kms.rst
> index 1ef7951ded5e..f4658417bf20 100644
> --- a/Documentation/gpu/drm-kms.rst
> +++ b/Documentation/gpu/drm-kms.rst
> @@ -545,9 +545,99 @@ Damage Tracking Properties
> Color Management Properties
> ---
>
> +Below is how a typical hardware pipeline for color
> +will look like:
> +
> +.. kernel-render:: DOT
> + :alt: Display Color Pipeline
> + :caption: Display Color Pipeline Overview
> +
> + digraph "KMS" {
> + node [shape=box]
> +
> + subgraph cluster_static {
> + style=dashed
> + label="Display Color Hardware Blocks"
> +
> + node [bgcolor=grey style=filled]
> + "Plane Degamma A" -> "Plane CSC/CTM A"
> + "Plane CSC/CTM A" -> "Plane Gamma A"
> + "Pipe Blender" [color=lightblue,style=filled, width=5.25,
> height=0.75];
> + "Plane Gamma A" -> "Pipe Blender"
> + "Pipe Blender" -> "Pipe DeGamma"
> + "Pipe DeGamma" -> "Pipe CSC/CTM"
> + "Pipe CSC/CTM" -> "Pipe Gamma"
> + "Pipe Gamma" -> "Pipe Output"
> + }
> +
> + subgraph cluster_static {
> + style=dashed
> +
> + node [shape=box]
> + "Plane Degamma B" -> "Plane CSC/CTM B"
> + "Plane CSC/CTM B" -> "Plane Gamma B"
> + "Plane Gamma B" -> "Pipe Blender"
> + }
> +
> + subgraph cluster_static {
> + style=dashed
> +
> + node [shape=box]
> + "Plane Degamma C" -> "Plane CSC/CTM C"
> + "Plane CSC/CTM C" -> "Plane Gamma C"
> + "Plane Gamma C" -> "Pipe Blender"
> + }
> +
> + subgraph cluster_fb {
> + style=dashed
> + label="RAM"
> +
> + node [shape=box width=1.7 height=0.2]
> +
> + "FB 1" -> "Plane Degamma A"
> + "FB 2" -> "Plane Degamma B"
> + "FB 3" -> "Plane Degamma C"
> + }
> + }
> +
> +In real world usecases,
> +
> +1. Plane Degamma can be used to linearize a non linear gamma
> +encoded framebuffer. This is needed to do any linear math like
> +color space conversion. For ex, linearize frames encoded in SRGB
> +or by HDR curve.
Hi,
Maybe better to avoid the term "gamma" as the curves are not always a
pure power function.
sRGB with a small s.
Thanks,
pq
> +
> +2. Later Plane CTM block can convert the content to some different
> +colorspace. For ex, SRGB to BT2020 etc.
> +
> +3. Plane Gamma block can be used later to re-apply the non-linear
> +curve. This can also be used to apply Tone Mapping for HDR usecases.
> +
> +All the layers or framebuffers need to be converted to same color
> +space and format before blending. The plane color hardware blocks
> +can help with this. Once the Data is blended, similar color processing
> +can be done on blended output using pipe color hardware blocks.
> +
> +DRM Properties have been created to define and expose all these
> +hardware blocks to userspace. A userspace application (compositor
> +or any color app) can use these interfaces and define policies to
> +efficiently use the display hardware for such color operations.
> +
> +Pipe Color Management Properties
> +-
> +
> .. kernel-doc:: drivers/gpu/drm/drm_color_mgmt.c
> :doc: overview
>
> +Plane Color Management Properties
> +-
> +
> +.. kernel-doc:: drivers/gpu/drm/drm_color_mgmt.c
> + :doc: Plane Color Properties
> +
> +.. kernel-doc:: drivers/gpu/drm/drm_color_mgmt.c
> + :doc: export
> +
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