[PATCH v6 2/2] Documentation/gpu: Add Synaptics tiling formats documentation

[Hsia-Jun Li]

From: Randy Li <ayaka at soulik.info>

Signed-off-by: Randy Li <ayaka at soulik.info>
Signed-off-by: Hsia-Jun(Randy) Li <randy.li at synaptics.com>
---
 Documentation/gpu/synaptics.rst | 81 +++++++++++++++++++++++++++++++++
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 create mode 100644 Documentation/gpu/synaptics.rst

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+.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
+
+================
+Synaptics Tiling
+================
+
+The tiling pixel formats in Synpatics Video Smart platform have
+many variants. Tiles could form the group of tiles, pixels within
+the group (nearest) width and height are stored into tile.
+Meanwhile, the tile in a group may not follow dimension layout,
+tile could form a small group of tiles, then that (sub)group
+of tiles would form a bigger group. We won't describe the dimension
+layout inside the group of tiles here. The layout of the group
+of tiles is fixed with the group width and height parameters
+in the same generation of the platform.
+
+Compression
+===========
+The proprietary lossless image compression protocol in Synaptics
+could minimizes the amount of data transferred (less memory bandwidth
+consumption) between devices. It would usually apply to the tiling
+pixel format.
+
+Each component would request an extra page aligned length buffer
+for storing the compression meta data. Also a 32 bytes parameters
+set would come with a compression meta data buffer.
+
+The component here corresponds to a signal type (i.e. Luma, chroma).
+They could be encoded into one or multiple metadata planes, but
+their compression parameters still would be individual.
+
+Pixel format modifiers
+======================
+Addition alignment requirement for stride and size of a memory plane
+could apply beyond what has been mentioned below. Remember always
+negotiating with all the devices in pipeline before allocation.
+
+.. flat-table:: Synpatics Image Format Modifiers
+
+	* - Identifier
+	  - Fourcc
+	  - Details
+
+	* - DRM_FORMAT_MOD_SYNA_V4H1
+	  - DRM_FORMAT_NV12
+	  - The plain uncompressed 8 bits tile format. It sounds similar to
+	Intel's Y-tile. but it won't take any pixel from the next X direction
+	in a tile group. The line stride and image height must be aligned to
+	a multiple of 16. The height of chrominance plane would plus 8.
+
+	* - DRM_FORMAT_MOD_SYNA_V4H3P8
+	  - DRM_FORMAT_NV15
+	  - The plain uncompressed 10 bits tile format. It stores pixel in 2D
+	3x4 tiles with a 8bits padding to each of tile. Then a tile is in a
+	128 bits cache line.
+
+	* - DRM_FORMAT_MOD_SYNA_V4H1_64L4_COMPRESSED
+	  - DRM_FORMAT_NV12
+	  - Group of tiles and compressed variant of ``DRM_FORMAT_MOD_SYNA_V4H1``.
+    A group of tiles would contain 64x4 pixels, where a tile has 1x4
+    pixel.
+
+	* - DRM_FORMAT_MOD_SYNA_V4H3P8_64L4_COMPRESSED
+	  - DRM_FORMAT_NV15
+	  - Group of tiles and compressed variant of ``DRM_FORMAT_MOD_SYNA_V4H3P8``.
+     A group of tiles would contains 48x4 pixels, where a tile has 3x4 pixels
+     and a 8 bits padding in the end of a tile. A group of tiles would
+     be 256 bytes.
+
+	* - ``DRM_FORMAT_MOD_SYNA_V4H1_128L128_COMPRESSED``
+	  - DRM_FORMAT_NV12
+	  - Group of tiles and compressed variant of ``DRM_FORMAT_MOD_SYNA_V4H1``.
+    A group of tiles would contain 128x32 pixels, where a tile has 1x4
+    pixel.
+
+	* - ``DRM_FORMAT_MOD_SYNA_V4H3P8_128L128_COMPRESSED``
+	  - DRM_FORMAT_NV15
+	  - Group of tiles and compressed variant of ``DRM_FORMAT_MOD_SYNA_V4H3P8``.
+     A group of tiles would contains 96x128 pixels, where a tile has 3x4 pixels
+     and a 8 bits padding in the end of a tile. A group of tiles would
+     be 16 KiB.
-- 
2.17.1