1 ====================== 1 ======================
2 AMDgpu Display Manager 2 AMDgpu Display Manager
3 ====================== 3 ======================
4 4
5 .. contents:: Table of Contents 5 .. contents:: Table of Contents
6 :depth: 3 6 :depth: 3
7 7
8 .. kernel-doc:: drivers/gpu/drm/amd/display/am 8 .. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
9 :doc: overview 9 :doc: overview
10 10
11 .. kernel-doc:: drivers/gpu/drm/amd/display/am 11 .. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
12 :internal: 12 :internal:
13 13
14 Lifecycle 14 Lifecycle
15 ========= 15 =========
16 16
17 .. kernel-doc:: drivers/gpu/drm/amd/display/am 17 .. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
18 :doc: DM Lifecycle 18 :doc: DM Lifecycle
19 19
20 .. kernel-doc:: drivers/gpu/drm/amd/display/am 20 .. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
21 :functions: dm_hw_init dm_hw_fini 21 :functions: dm_hw_init dm_hw_fini
22 22
23 Interrupts 23 Interrupts
24 ========== 24 ==========
25 25
26 .. kernel-doc:: drivers/gpu/drm/amd/display/am 26 .. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_irq.c
27 :doc: overview 27 :doc: overview
28 28
29 .. kernel-doc:: drivers/gpu/drm/amd/display/am 29 .. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_irq.c
30 :internal: 30 :internal:
31 31
32 .. kernel-doc:: drivers/gpu/drm/amd/display/am 32 .. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
33 :functions: register_hpd_handlers dm_crtc_h 33 :functions: register_hpd_handlers dm_crtc_high_irq dm_pflip_high_irq
34 34
35 Atomic Implementation 35 Atomic Implementation
36 ===================== 36 =====================
37 37
38 .. kernel-doc:: drivers/gpu/drm/amd/display/am 38 .. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
39 :doc: atomic 39 :doc: atomic
40 40
41 .. kernel-doc:: drivers/gpu/drm/amd/display/am 41 .. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
42 :functions: amdgpu_dm_atomic_check amdgpu_d 42 :functions: amdgpu_dm_atomic_check amdgpu_dm_atomic_commit_tail
43 43
44 Color Management Properties 44 Color Management Properties
45 =========================== 45 ===========================
46 46
47 .. kernel-doc:: drivers/gpu/drm/amd/display/am 47 .. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c
48 :doc: overview 48 :doc: overview
49 49
50 .. kernel-doc:: drivers/gpu/drm/amd/display/am 50 .. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c
51 :internal: 51 :internal:
52 52
53 53
54 DC Color Capabilities between DCN generations 54 DC Color Capabilities between DCN generations
55 --------------------------------------------- 55 ---------------------------------------------
56 56
57 DRM/KMS framework defines three CRTC color cor 57 DRM/KMS framework defines three CRTC color correction properties: degamma,
58 color transformation matrix (CTM) and gamma, a 58 color transformation matrix (CTM) and gamma, and two properties for degamma and
59 gamma LUT sizes. AMD DC programs some of the c 59 gamma LUT sizes. AMD DC programs some of the color correction features
60 pre-blending but DRM/KMS has not per-plane col 60 pre-blending but DRM/KMS has not per-plane color correction properties.
61 61
62 In general, the DRM CRTC color properties are 62 In general, the DRM CRTC color properties are programmed to DC, as follows:
63 CRTC gamma after blending, and CRTC degamma pr 63 CRTC gamma after blending, and CRTC degamma pre-blending. Although CTM is
64 programmed after blending, it is mapped to DPP 64 programmed after blending, it is mapped to DPP hw blocks (pre-blending). Other
65 color caps available in the hw is not currentl 65 color caps available in the hw is not currently exposed by DRM interface and
66 are bypassed. 66 are bypassed.
67 67
68 .. kernel-doc:: drivers/gpu/drm/amd/display/dc 68 .. kernel-doc:: drivers/gpu/drm/amd/display/dc/dc.h
69 :doc: color-management-caps 69 :doc: color-management-caps
70 70
71 .. kernel-doc:: drivers/gpu/drm/amd/display/dc 71 .. kernel-doc:: drivers/gpu/drm/amd/display/dc/dc.h
72 :internal: 72 :internal:
73 73
74 The color pipeline has undergone major changes 74 The color pipeline has undergone major changes between DCN hardware
75 generations. What's possible to do before and 75 generations. What's possible to do before and after blending depends on
76 hardware capabilities, as illustrated below by 76 hardware capabilities, as illustrated below by the DCN 2.0 and DCN 3.0 families
77 schemas. 77 schemas.
78 78
79 **DCN 2.0 family color caps and mapping** 79 **DCN 2.0 family color caps and mapping**
80 80
81 .. kernel-figure:: dcn2_cm_drm_current.svg 81 .. kernel-figure:: dcn2_cm_drm_current.svg
82 82
83 **DCN 3.0 family color caps and mapping** 83 **DCN 3.0 family color caps and mapping**
84 84
85 .. kernel-figure:: dcn3_cm_drm_current.svg 85 .. kernel-figure:: dcn3_cm_drm_current.svg
86 86
87 Blend Mode Properties 87 Blend Mode Properties
88 ===================== 88 =====================
89 89
90 Pixel blend mode is a DRM plane composition pr 90 Pixel blend mode is a DRM plane composition property of :c:type:`drm_plane` used to
91 describes how pixels from a foreground plane ( 91 describes how pixels from a foreground plane (fg) are composited with the
92 background plane (bg). Here, we present main c 92 background plane (bg). Here, we present main concepts of DRM blend mode to help
93 to understand how this property is mapped to A 93 to understand how this property is mapped to AMD DC interface. See more about
94 this DRM property and the alpha blending equat 94 this DRM property and the alpha blending equations in :ref:`DRM Plane
95 Composition Properties <plane_composition_prop 95 Composition Properties <plane_composition_properties>`.
96 96
97 Basically, a blend mode sets the alpha blendin 97 Basically, a blend mode sets the alpha blending equation for plane
98 composition that fits the mode in which the al 98 composition that fits the mode in which the alpha channel affects the state of
99 pixel color values and, therefore, the resulte 99 pixel color values and, therefore, the resulted pixel color. For
100 example, consider the following elements of th 100 example, consider the following elements of the alpha blending equation:
101 101
102 - *fg.rgb*: Each of the RGB component values f 102 - *fg.rgb*: Each of the RGB component values from the foreground's pixel.
103 - *fg.alpha*: Alpha component value from the f 103 - *fg.alpha*: Alpha component value from the foreground's pixel.
104 - *bg.rgb*: Each of the RGB component values f 104 - *bg.rgb*: Each of the RGB component values from the background.
105 - *plane_alpha*: Plane alpha value set by the 105 - *plane_alpha*: Plane alpha value set by the **plane "alpha" property**, see
106 more in :ref:`DRM Plane Composition Properti 106 more in :ref:`DRM Plane Composition Properties <plane_composition_properties>`.
107 107
108 in the basic alpha blending equation:: 108 in the basic alpha blending equation::
109 109
110 out.rgb = alpha * fg.rgb + (1 - alpha) * bg 110 out.rgb = alpha * fg.rgb + (1 - alpha) * bg.rgb
111 111
112 the alpha channel value of each pixel in a pla 112 the alpha channel value of each pixel in a plane is ignored and only the plane
113 alpha affects the resulted pixel color values. 113 alpha affects the resulted pixel color values.
114 114
115 DRM has three blend mode to define the blend f 115 DRM has three blend mode to define the blend formula in the plane composition:
116 116
117 * **None**: Blend formula that ignores the pix 117 * **None**: Blend formula that ignores the pixel alpha.
118 118
119 * **Pre-multiplied**: Blend formula that assum 119 * **Pre-multiplied**: Blend formula that assumes the pixel color values in a
120 plane was already pre-multiplied by its own 120 plane was already pre-multiplied by its own alpha channel before storage.
121 121
122 * **Coverage**: Blend formula that assumes the 122 * **Coverage**: Blend formula that assumes the pixel color values were not
123 pre-multiplied with the alpha channel values 123 pre-multiplied with the alpha channel values.
124 124
125 and pre-multiplied is the default pixel blend 125 and pre-multiplied is the default pixel blend mode, that means, when no blend
126 mode property is created or defined, DRM consi 126 mode property is created or defined, DRM considers the plane's pixels has
127 pre-multiplied color values. On IGT GPU tools, 127 pre-multiplied color values. On IGT GPU tools, the kms_plane_alpha_blend test
128 provides a set of subtests to verify plane alp 128 provides a set of subtests to verify plane alpha and blend mode properties.
129 129
130 The DRM blend mode and its elements are then m 130 The DRM blend mode and its elements are then mapped by AMDGPU display manager
131 (DM) to program the blending configuration of 131 (DM) to program the blending configuration of the Multiple Pipe/Plane Combined
132 (MPC), as follows: 132 (MPC), as follows:
133 133
134 .. kernel-doc:: drivers/gpu/drm/amd/display/dc 134 .. kernel-doc:: drivers/gpu/drm/amd/display/dc/inc/hw/mpc.h
135 :identifiers: mpcc_blnd_cfg 135 :identifiers: mpcc_blnd_cfg
136 136
137 Therefore, the blending configuration for a si 137 Therefore, the blending configuration for a single MPCC instance on the MPC
138 tree is defined by :c:type:`mpcc_blnd_cfg`, wh 138 tree is defined by :c:type:`mpcc_blnd_cfg`, where
139 :c:type:`pre_multiplied_alpha` is the alpha pr 139 :c:type:`pre_multiplied_alpha` is the alpha pre-multiplied mode flag used to
140 set :c:type:`MPCC_ALPHA_MULTIPLIED_MODE`. It c 140 set :c:type:`MPCC_ALPHA_MULTIPLIED_MODE`. It controls whether alpha is
141 multiplied (true/false), being only true for D 141 multiplied (true/false), being only true for DRM pre-multiplied blend mode.
142 :c:type:`mpcc_alpha_blend_mode` defines the al 142 :c:type:`mpcc_alpha_blend_mode` defines the alpha blend mode regarding pixel
143 alpha and plane alpha values. It sets one of t 143 alpha and plane alpha values. It sets one of the three modes for
144 :c:type:`MPCC_ALPHA_BLND_MODE`, as described b 144 :c:type:`MPCC_ALPHA_BLND_MODE`, as described below.
145 145
146 .. kernel-doc:: drivers/gpu/drm/amd/display/dc 146 .. kernel-doc:: drivers/gpu/drm/amd/display/dc/inc/hw/mpc.h
147 :identifiers: mpcc_alpha_blend_mode 147 :identifiers: mpcc_alpha_blend_mode
148 148
149 DM then maps the elements of `enum mpcc_alpha_ 149 DM then maps the elements of `enum mpcc_alpha_blend_mode` to those in the DRM
150 blend formula, as follows: 150 blend formula, as follows:
151 151
152 * *MPC pixel alpha* matches *DRM fg.alpha* as 152 * *MPC pixel alpha* matches *DRM fg.alpha* as the alpha component value
153 from the plane's pixel 153 from the plane's pixel
154 * *MPC global alpha* matches *DRM plane_alpha* 154 * *MPC global alpha* matches *DRM plane_alpha* when the pixel alpha should
155 be ignored and, therefore, pixel values are 155 be ignored and, therefore, pixel values are not pre-multiplied
156 * *MPC global gain* assumes *MPC global alpha* 156 * *MPC global gain* assumes *MPC global alpha* value when both *DRM
157 fg.alpha* and *DRM plane_alpha* participate 157 fg.alpha* and *DRM plane_alpha* participate in the blend equation
158 158
159 In short, *fg.alpha* is ignored by selecting 159 In short, *fg.alpha* is ignored by selecting
160 :c:type:`MPCC_ALPHA_BLEND_MODE_GLOBAL_ALPHA`. 160 :c:type:`MPCC_ALPHA_BLEND_MODE_GLOBAL_ALPHA`. On the other hand, (plane_alpha *
161 fg.alpha) component becomes available by selec 161 fg.alpha) component becomes available by selecting
162 :c:type:`MPCC_ALPHA_BLEND_MODE_PER_PIXEL_ALPHA 162 :c:type:`MPCC_ALPHA_BLEND_MODE_PER_PIXEL_ALPHA_COMBINED_GLOBAL_GAIN`. And the
163 :c:type:`MPCC_ALPHA_MULTIPLIED_MODE` defines i 163 :c:type:`MPCC_ALPHA_MULTIPLIED_MODE` defines if the pixel color values are
164 pre-multiplied by alpha or not. 164 pre-multiplied by alpha or not.
165 165
166 Blend configuration flow 166 Blend configuration flow
167 ------------------------ 167 ------------------------
168 168
169 The alpha blending equation is configured from 169 The alpha blending equation is configured from DRM to DC interface by the
170 following path: 170 following path:
171 171
172 1. When updating a :c:type:`drm_plane_state <d 172 1. When updating a :c:type:`drm_plane_state <drm_plane_state>`, DM calls
173 :c:type:`amdgpu_dm_plane_fill_blending_from 173 :c:type:`amdgpu_dm_plane_fill_blending_from_plane_state()` that maps
174 :c:type:`drm_plane_state <drm_plane_state>` 174 :c:type:`drm_plane_state <drm_plane_state>` attributes to
175 :c:type:`dc_plane_info <dc_plane_info>` str 175 :c:type:`dc_plane_info <dc_plane_info>` struct to be handled in the
176 OS-agnostic component (DC). 176 OS-agnostic component (DC).
177 177
178 2. On DC interface, :c:type:`struct mpcc_blnd_ 178 2. On DC interface, :c:type:`struct mpcc_blnd_cfg <mpcc_blnd_cfg>` programs the
179 MPCC blend configuration considering the :c 179 MPCC blend configuration considering the :c:type:`dc_plane_info
180 <dc_plane_info>` input from DPP. 180 <dc_plane_info>` input from DPP.
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