184 lines
7.0 KiB
ReStructuredText
184 lines
7.0 KiB
ReStructuredText
======================
|
|
AMDgpu Display Manager
|
|
======================
|
|
|
|
.. contents:: Table of Contents
|
|
:depth: 3
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
|
|
:doc: overview
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
|
|
:internal:
|
|
|
|
Lifecycle
|
|
=========
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
|
|
:doc: DM Lifecycle
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
|
|
:functions: dm_hw_init dm_hw_fini
|
|
|
|
Interrupts
|
|
==========
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_irq.c
|
|
:doc: overview
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_irq.c
|
|
:internal:
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
|
|
:functions: register_hpd_handlers dm_crtc_high_irq dm_pflip_high_irq
|
|
|
|
Atomic Implementation
|
|
=====================
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
|
|
:doc: atomic
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
|
|
:functions: amdgpu_dm_atomic_check amdgpu_dm_atomic_commit_tail
|
|
|
|
Color Management Properties
|
|
===========================
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c
|
|
:doc: overview
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c
|
|
:internal:
|
|
|
|
|
|
DC Color Capabilities between DCN generations
|
|
---------------------------------------------
|
|
|
|
DRM/KMS framework defines three CRTC color correction properties: degamma,
|
|
color transformation matrix (CTM) and gamma, and two properties for degamma and
|
|
gamma LUT sizes. AMD DC programs some of the color correction features
|
|
pre-blending but DRM/KMS has not per-plane color correction properties.
|
|
|
|
In general, the DRM CRTC color properties are programmed to DC, as follows:
|
|
CRTC gamma after blending, and CRTC degamma pre-blending. Although CTM is
|
|
programmed after blending, it is mapped to DPP hw blocks (pre-blending). Other
|
|
color caps available in the hw is not currently exposed by DRM interface and
|
|
are bypassed.
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/amd/display/dc/dc.h
|
|
:doc: color-management-caps
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/amd/display/dc/dc.h
|
|
:internal:
|
|
|
|
The color pipeline has undergone major changes between DCN hardware
|
|
generations. What's possible to do before and after blending depends on
|
|
hardware capabilities, as illustrated below by the DCN 2.0 and DCN 3.0 families
|
|
schemas.
|
|
|
|
**DCN 2.0 family color caps and mapping**
|
|
|
|
.. kernel-figure:: dcn2_cm_drm_current.svg
|
|
|
|
**DCN 3.0 family color caps and mapping**
|
|
|
|
.. kernel-figure:: dcn3_cm_drm_current.svg
|
|
|
|
Blend Mode Properties
|
|
=====================
|
|
|
|
Pixel blend mode is a DRM plane composition property of :c:type:`drm_plane` used to
|
|
describes how pixels from a foreground plane (fg) are composited with the
|
|
background plane (bg). Here, we present main concepts of DRM blend mode to help
|
|
to understand how this property is mapped to AMD DC interface. See more about
|
|
this DRM property and the alpha blending equations in :ref:`DRM Plane
|
|
Composition Properties <plane_composition_properties>`.
|
|
|
|
Basically, a blend mode sets the alpha blending equation for plane
|
|
composition that fits the mode in which the alpha channel affects the state of
|
|
pixel color values and, therefore, the resulted pixel color. For
|
|
example, consider the following elements of the alpha blending equation:
|
|
|
|
- *fg.rgb*: Each of the RGB component values from the foreground's pixel.
|
|
- *fg.alpha*: Alpha component value from the foreground's pixel.
|
|
- *bg.rgb*: Each of the RGB component values from the background.
|
|
- *plane_alpha*: Plane alpha value set by the **plane "alpha" property**, see
|
|
more in :ref:`DRM Plane Composition Properties <plane_composition_properties>`.
|
|
|
|
in the basic alpha blending equation::
|
|
|
|
out.rgb = alpha * fg.rgb + (1 - alpha) * bg.rgb
|
|
|
|
the alpha channel value of each pixel in a plane is ignored and only the plane
|
|
alpha affects the resulted pixel color values.
|
|
|
|
DRM has three blend mode to define the blend formula in the plane composition:
|
|
|
|
* **None**: Blend formula that ignores the pixel alpha.
|
|
|
|
* **Pre-multiplied**: Blend formula that assumes the pixel color values in a
|
|
plane was already pre-multiplied by its own alpha channel before storage.
|
|
|
|
* **Coverage**: Blend formula that assumes the pixel color values were not
|
|
pre-multiplied with the alpha channel values.
|
|
|
|
and pre-multiplied is the default pixel blend mode, that means, when no blend
|
|
mode property is created or defined, DRM considers the plane's pixels has
|
|
pre-multiplied color values. On IGT GPU tools, the kms_plane_alpha_blend test
|
|
provides a set of subtests to verify plane alpha and blend mode properties.
|
|
|
|
The DRM blend mode and its elements are then mapped by AMDGPU display manager
|
|
(DM) to program the blending configuration of the Multiple Pipe/Plane Combined
|
|
(MPC), as follows:
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/amd/display/dc/inc/hw/mpc.h
|
|
:doc: mpc-overview
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/amd/display/dc/inc/hw/mpc.h
|
|
:functions: mpcc_blnd_cfg
|
|
|
|
Therefore, the blending configuration for a single MPCC instance on the MPC
|
|
tree is defined by :c:type:`mpcc_blnd_cfg`, where
|
|
:c:type:`pre_multiplied_alpha` is the alpha pre-multiplied mode flag used to
|
|
set :c:type:`MPCC_ALPHA_MULTIPLIED_MODE`. It controls whether alpha is
|
|
multiplied (true/false), being only true for DRM pre-multiplied blend mode.
|
|
:c:type:`mpcc_alpha_blend_mode` defines the alpha blend mode regarding pixel
|
|
alpha and plane alpha values. It sets one of the three modes for
|
|
:c:type:`MPCC_ALPHA_BLND_MODE`, as described below.
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/amd/display/dc/inc/hw/mpc.h
|
|
:functions: mpcc_alpha_blend_mode
|
|
|
|
DM then maps the elements of `enum mpcc_alpha_blend_mode` to those in the DRM
|
|
blend formula, as follows:
|
|
|
|
* *MPC pixel alpha* matches *DRM fg.alpha* as the alpha component value
|
|
from the plane's pixel
|
|
* *MPC global alpha* matches *DRM plane_alpha* when the pixel alpha should
|
|
be ignored and, therefore, pixel values are not pre-multiplied
|
|
* *MPC global gain* assumes *MPC global alpha* value when both *DRM
|
|
fg.alpha* and *DRM plane_alpha* participate in the blend equation
|
|
|
|
In short, *fg.alpha* is ignored by selecting
|
|
:c:type:`MPCC_ALPHA_BLEND_MODE_GLOBAL_ALPHA`. On the other hand, (plane_alpha *
|
|
fg.alpha) component becomes available by selecting
|
|
:c:type:`MPCC_ALPHA_BLEND_MODE_PER_PIXEL_ALPHA_COMBINED_GLOBAL_GAIN`. And the
|
|
:c:type:`MPCC_ALPHA_MULTIPLIED_MODE` defines if the pixel color values are
|
|
pre-multiplied by alpha or not.
|
|
|
|
Blend configuration flow
|
|
------------------------
|
|
|
|
The alpha blending equation is configured from DRM to DC interface by the
|
|
following path:
|
|
|
|
1. When updating a :c:type:`drm_plane_state <drm_plane_state>`, DM calls
|
|
:c:type:`amdgpu_dm_plane_fill_blending_from_plane_state()` that maps
|
|
:c:type:`drm_plane_state <drm_plane_state>` attributes to
|
|
:c:type:`dc_plane_info <dc_plane_info>` struct to be handled in the
|
|
OS-agnostic component (DC).
|
|
|
|
2. On DC interface, :c:type:`struct mpcc_blnd_cfg <mpcc_blnd_cfg>` programs the
|
|
MPCC blend configuration considering the :c:type:`dc_plane_info
|
|
<dc_plane_info>` input from DPP.
|