lib/igt_kms: Briefly describe Intel-to-DRM mapping between pipes, encoders and connectors. Signed-off-by: Marius Vlad <marius.c.vlad@xxxxxxxxx> --- lib/igt_kms.c | 82 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 82 insertions(+) diff --git a/lib/igt_kms.c b/lib/igt_kms.c index c7a0b77..caa8837 100644 --- a/lib/igt_kms.c +++ b/lib/igt_kms.c @@ -68,6 +68,88 @@ * functions have all igt_ prefixes. This part is still very much work in * progress and so also lacks a bit documentation for the individual functions. * + * Intel/DRM terminology and display connections: + * + * Intel documentation describes the road from memory to an output connector as + * follows: + * + * |[!<-- language="C" --> + * .--------. .-------. .-------------. .-----. + * | Memory |---->| Pipes |---->| Transcoders |---->| DDI | + * '--------' '-------' '-------------' '-----' + * ]| + * + * Pipes represent the front-end of the display contain the planes, blending, + * and color correction, while the transcoders contain timing generators, + * encoders, A/V mixers and PSR (Panel-Self Refresh) controllers. Finally the + * DDI represent the connectors attached to the display. + * + * + * In DRM we have the following: + * + * |[!<-- language="C" --> + * .-----------. .-------. .-----------. .------------. + * | Framebuff |---->| Pipes |---->| Encoders |---->| Connectors | + * '-----------' '-------' '-----------' '------------' + * ]| + * + * + * The frame buffer ties a reference to a memory object and provides a pointer + * to the actual data. + * + * The pipe is used to set the display mode, timings and gamma tables. On some + * hardware models this is tied with the transcoder. In DRM-parlance this is + * referred as a CRTC. + * + * Each pipe has multiple planes. On older hardware these planes where known as + * primary plane, overlay/sprite plane, and cursor plane. From GEN9 (SKL/BXT) + * each pipe has three planes and a cursor plane. Each plane can be used as a + * primary, as a sprite or as an overlay plane. The planes are the ones that + * retrieve the pixels from memory and pushes them to the encoder. + * + * A pipe prior to GEN9: + * + * |[!<-- language="C" --> + * .--------. + * | Memory | .--------. + * | |------------>| Cursor |------>... + * | | '--------' + * | | + * | | .--------. + * | |-------->| Sprite |---------->... + * | | '--------' + * | | + * | | .---------. + * | |----->| Primary |------------>... + * | | '---------' + * '--------' + * ]| + * + * A pipe with universal planes: + * + * |[!<-- language="C" --> + * .--------. + * | Memory | .--------. + * | |------------>| Cursor |------>... + * | | '--------' + * | | + * | | .-------. + * | |-------->| Plane |---------->... + * | | '-------' + * | | + * | | .-------. + * | |----->| Plane |------------>... + * | | '-------' + * '--------' + * ]| + * + * The encoder is used to convert, depending on the output, pixels from pipes + * to signals understood by the connector. + * + * The connector will connect to the output display. This contains information + * about the attached display such as EDID, DPMS and information about modes + * supported by the display. + * * Note that this library's header pulls in the [i-g-t * framebuffer](intel-gpu-tools-Framebuffer.html) library as a * dependency. -- 2.6.2 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
