Documentation/devicetree/bindings/media/video-interface-devices.yaml

   1 # SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
   2 %YAML 1.2
   3 ---
   4 $id: http://devicetree.org/schemas/media/video-interface-devices.yaml#
   5 $schema: http://devicetree.org/meta-schemas/core.yaml#
   6
   7 title: Common bindings for video receiver and transmitter devices
   8
   9 maintainers:
  10   - Jacopo Mondi <jacopo@jmondi.org>
  11   - Sakari Ailus <sakari.ailus@linux.intel.com>
  12
  13 properties:
  14   flash-leds:
  15     $ref: /schemas/types.yaml#/definitions/phandle-array
  16     description:
  17       An array of phandles, each referring to a flash LED, a sub-node of the LED
  18       driver device node.
  19
  20   lens-focus:
  21     $ref: /schemas/types.yaml#/definitions/phandle
  22     description:
  23       A phandle to the node of the focus lens controller.
  24
  25   rotation:
  26     $ref: /schemas/types.yaml#/definitions/uint32
  27     enum: [ 0, 90, 180, 270 ]
  28     description: |
  29       The camera rotation is expressed as the angular difference in degrees
  30       between two reference systems, one relative to the camera module, and one
  31       defined on the external world scene to be captured when projected on the
  32       image sensor pixel array.
  33
  34       A camera sensor has a 2-dimensional reference system 'Rc' defined by its
  35       pixel array read-out order. The origin is set to the first pixel being
  36       read out, the X-axis points along the column read-out direction towards
  37       the last columns, and the Y-axis along the row read-out direction towards
  38       the last row.
  39
  40       A typical example for a sensor with a 2592x1944 pixel array matrix
  41       observed from the front is:
  42
  43               2591       X-axis          0
  44                 <------------------------+ 0
  45                 .......... ... ..........!
  46                 .......... ... ..........! Y-axis
  47                            ...           !
  48                 .......... ... ..........!
  49                 .......... ... ..........! 1943
  50                                          V
  51
  52       The external world scene reference system 'Rs' is a 2-dimensional
  53       reference system on the focal plane of the camera module. The origin is
  54       placed on the top-left corner of the visible scene, the X-axis points
  55       towards the right, and the Y-axis points towards the bottom of the scene.
  56       The top, bottom, left and right directions are intentionally not defined
  57       and depend on the environment in which the camera is used.
  58
  59       A typical example of a (very common) picture of a shark swimming from left
  60       to right, as seen from the camera, is:
  61
  62                0               X-axis
  63              0 +------------------------------------->
  64                !
  65                !
  66                !
  67                !           |\____)\___
  68                !           ) _____  __`<
  69                !           |/     )/
  70                !
  71                !
  72                !
  73                V
  74              Y-axis
  75
  76       with the reference system 'Rs' placed on the camera focal plane:
  77
  78                                   ¸.·˙!
  79                               ¸.·˙    !
  80                   _       ¸.·˙        !
  81                +-/ \-+¸.·˙            !
  82                | (o) |                ! Camera focal plane
  83                +-----+˙·.¸            !
  84                           ˙·.¸        !
  85                               ˙·.¸    !
  86                                   ˙·.¸!
  87
  88       When projected on the sensor's pixel array, the image and the associated
  89       reference system 'Rs' are typically (but not always) inverted, due to the
  90       camera module's lens optical inversion effect.
  91
  92       Assuming the above represented scene of the swimming shark, the lens
  93       inversion projects the scene and its reference system onto the sensor
  94       pixel array, seen from the front of the camera sensor, as follows:
  95
  96             Y-axis
  97                ^
  98                !
  99                !
 100                !
 101                !            |\_____)\__
 102                !            ) ____  ___.<
 103                !            |/    )/
 104                !
 105                !
 106                !
 107              0 +------------------------------------->
 108                0               X-axis
 109
 110       Note the shark being upside-down.
 111
 112       The resulting projected reference system is named 'Rp'.
 113
 114       The camera rotation property is then defined as the angular difference in
 115       the counter-clockwise direction between the camera reference system 'Rc'
 116       and the projected scene reference system 'Rp'. It is expressed in degrees
 117       as a number in the range [0, 360[.
 118
 119       Examples
 120
 121       0 degrees camera rotation:
 122
 123
 124                     Y-Rp
 125                      ^
 126               Y-Rc   !
 127                ^     !
 128                !     !
 129                !     !
 130                !     !
 131                !     !
 132                !     !
 133                !     !
 134                !     !
 135                !   0 +------------------------------------->
 136                !     0               X-Rp
 137              0 +------------------------------------->
 138                0               X-Rc
 139
 140
 141                                 X-Rc                0
 142                <------------------------------------+ 0
 143                            X-Rp                 0   !
 144            <------------------------------------+ 0 !
 145                                                 !   !
 146                                                 !   !
 147                                                 !   !
 148                                                 !   !
 149                                                 !   !
 150                                                 !   !
 151                                                 !   !
 152                                                 !   V
 153                                                 !  Y-Rc
 154                                                 V
 155                                                Y-Rp
 156
 157       90 degrees camera rotation:
 158
 159                0        Y-Rc
 160              0 +-------------------->
 161                !   Y-Rp
 162                !    ^
 163                !    !
 164                !    !
 165                !    !
 166                !    !
 167                !    !
 168                !    !
 169                !    !
 170                !    !
 171                !    !
 172                !  0 +------------------------------------->
 173                !    0              X-Rp
 174                !
 175                !
 176                !
 177                !
 178                V
 179               X-Rc
 180
 181       180 degrees camera rotation:
 182
 183                                             0
 184        <------------------------------------+ 0
 185                         X-Rc                !
 186               Y-Rp                          !
 187                ^                            !
 188                !                            !
 189                !                            !
 190                !                            !
 191                !                            !
 192                !                            !
 193                !                            !
 194                !                            V
 195                !                           Y-Rc
 196              0 +------------------------------------->
 197                0              X-Rp
 198
 199       270 degrees camera rotation:
 200
 201                0        Y-Rc
 202              0 +-------------------->
 203                !                                        0
 204                !    <-----------------------------------+ 0
 205                !                    X-Rp                !
 206                !                                        !
 207                !                                        !
 208                !                                        !
 209                !                                        !
 210                !                                        !
 211                !                                        !
 212                !                                        !
 213                !                                        !
 214                !                                        V
 215                !                                       Y-Rp
 216                !
 217                !
 218                !
 219                !
 220                V
 221               X-Rc
 222
 223
 224       Example one - Webcam
 225
 226       A camera module installed on the user facing part of a laptop screen
 227       casing used for video calls. The captured images are meant to be displayed
 228       in landscape mode (width > height) on the laptop screen.
 229
 230       The camera is typically mounted upside-down to compensate the lens optical
 231       inversion effect:
 232
 233                     Y-Rp
 234               Y-Rc   ^
 235                ^     !
 236                !     !
 237                !     !       |\_____)\__
 238                !     !       ) ____  ___.<
 239                !     !       |/    )/
 240                !     !
 241                !     !
 242                !     !
 243                !   0 +------------------------------------->
 244                !     0           X-Rp
 245              0 +------------------------------------->
 246                0            X-Rc
 247
 248       The two reference systems are aligned, the resulting camera rotation is
 249       0 degrees, no rotation correction needs to be applied to the resulting
 250       image once captured to memory buffers to correctly display it to users:
 251
 252                +--------------------------------------+
 253                !                                      !
 254                !                                      !
 255                !                                      !
 256                !             |\____)\___              !
 257                !             ) _____  __`<            !
 258                !             |/     )/                !
 259                !                                      !
 260                !                                      !
 261                !                                      !
 262                +--------------------------------------+
 263
 264       If the camera sensor is not mounted upside-down to compensate for the lens
 265       optical inversion, the two reference systems will not be aligned, with
 266       'Rp' being rotated 180 degrees relatively to 'Rc':
 267
 268
 269                         X-Rc                0
 270        <------------------------------------+ 0
 271                                             !
 272               Y-Rp                          !
 273                ^                            !
 274                !                            !
 275                !       |\_____)\__          !
 276                !       ) ____  ___.<        !
 277                !       |/    )/             !
 278                !                            !
 279                !                            !
 280                !                            V
 281                !                           Y-Rc
 282              0 +------------------------------------->
 283                0            X-Rp
 284
 285       The image once captured to memory will then be rotated by 180 degrees:
 286
 287                +--------------------------------------+
 288                !                                      !
 289                !                                      !
 290                !                                      !
 291                !              __/(_____/|             !
 292                !            >.___  ____ (             !
 293                !                 \(    \|             !
 294                !                                      !
 295                !                                      !
 296                !                                      !
 297                +--------------------------------------+
 298
 299       A software rotation correction of 180 degrees should be applied to
 300       correctly display the image:
 301
 302                +--------------------------------------+
 303                !                                      !
 304                !                                      !
 305                !                                      !
 306                !             |\____)\___              !
 307                !             ) _____  __`<            !
 308                !             |/     )/                !
 309                !                                      !
 310                !                                      !
 311                !                                      !
 312                +--------------------------------------+
 313
 314       Example two - Phone camera
 315
 316       A camera installed on the back side of a mobile device facing away from
 317       the user. The captured images are meant to be displayed in portrait mode
 318       (height > width) to match the device screen orientation and the device
 319       usage orientation used when taking the picture.
 320
 321       The camera sensor is typically mounted with its pixel array longer side
 322       aligned to the device longer side, upside-down mounted to compensate for
 323       the lens optical inversion effect:
 324
 325                0        Y-Rc
 326              0 +-------------------->
 327                !   Y-Rp
 328                !    ^
 329                !    !
 330                !    !
 331                !    !
 332                !    !            |\_____)\__
 333                !    !            ) ____  ___.<
 334                !    !            |/    )/
 335                !    !
 336                !    !
 337                !    !
 338                !  0 +------------------------------------->
 339                !    0                X-Rp
 340                !
 341                !
 342                !
 343                !
 344                V
 345               X-Rc
 346
 347       The two reference systems are not aligned and the 'Rp' reference system is
 348       rotated by 90 degrees in the counter-clockwise direction relatively to the
 349       'Rc' reference system.
 350
 351       The image once captured to memory will be rotated:
 352
 353                +-------------------------------------+
 354                |                 _ _                 |
 355                |                \   /                |
 356                |                 | |                 |
 357                |                 | |                 |
 358                |                 |  >                |
 359                |                <  |                 |
 360                |                 | |                 |
 361                |                   .                 |
 362                |                  V                  |
 363                +-------------------------------------+
 364
 365       A correction of 90 degrees in counter-clockwise direction has to be
 366       applied to correctly display the image in portrait mode on the device
 367       screen:
 368
 369                         +--------------------+
 370                         |                    |
 371                         |                    |
 372                         |                    |
 373                         |                    |
 374                         |                    |
 375                         |                    |
 376                         |   |\____)\___      |
 377                         |   ) _____  __`<    |
 378                         |   |/     )/        |
 379                         |                    |
 380                         |                    |
 381                         |                    |
 382                         |                    |
 383                         |                    |
 384                         +--------------------+
 385
 386   orientation:
 387     description:
 388       The orientation of a device (typically an image sensor or a flash LED)
 389       describing its mounting position relative to the usage orientation of the
 390       system where the device is installed on.
 391     $ref: /schemas/types.yaml#/definitions/uint32
 392     enum:
 393         # Front. The device is mounted on the front facing side of the system. For
 394         # mobile devices such as smartphones, tablets and laptops the front side
 395         # is the user facing side.
 396       - 0
 397         # Back. The device is mounted on the back side of the system, which is
 398         # defined as the opposite side of the front facing one.
 399       - 1
 400         # External. The device is not attached directly to the system but is
 401         # attached in a way that allows it to move freely.
 402       - 2
 403
 404 additionalProperties: true
 405
 406 ...