mainlining shenanigans
85bdcb7eaa
The quantization tables as defined in the file (luma_q_table, chroma_q_table) are in fact in linear order. The JPEG file header, which is not generated by the hardware, but must be programatically created with the CPU, expects the table in zigzag order. On the other hand, the hardware doesn't expect neither linear, nor zigzag order. Instead it expects the quantization tables in vertical groups of four quantization parameters, and the groups are organized in blocks of two vertically adjacent groups. On top of that the blocks must be provided to the hardware in this order: leftmost top block, leftmost bottom block, second leftmost top block, second leftmost bottom block and so on. So, if this is the quantization table in linear order: 0x10, 0x0b, 0x0a, 0x10, 0x18, 0x28, 0x33, 0x3d, 0x0c, 0x0c, 0x0e, 0x13, 0x1a, 0x3a, 0x3c, 0x37, 0x0e, 0x0d, 0x10, 0x18, 0x28, 0x39, 0x45, 0x38, 0x0e, 0x11, 0x16, 0x1d, 0x33, 0x57, 0x50, 0x3e, 0x12, 0x16, 0x25, 0x38, 0x44, 0x6d, 0x67, 0x4d, 0x18, 0x23, 0x37, 0x40, 0x51, 0x68, 0x71, 0x5c, 0x31, 0x40, 0x4e, 0x57, 0x67, 0x79, 0x78, 0x65, 0x48, 0x5c, 0x5f, 0x62, 0x70, 0x64, 0x67, 0x63 then the hardware expects this in its consecutive registers: 0x100c0e0e, 0x0b0c0d11, 0x12183148, 0x1623405c, 0x0a0e1016, 0x1013181d, 0x25374e5f, 0x38405762, and so on. Consequently, the same area of memory cannot be used both for dumping it into the JPEG file header and writing its contents to the hardware registers. Instead, a separate pair of arrays is added for properly reordered quantization tables, to be read with get_unaligned_be32() and linearly written to the registers. The "ctx" parameter is not needed any more for hantro_jpeg_get_qtable(). Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@collabora.com> Tested-by: Ezequiel Garcia <ezequiel@collabora.com> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> |
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Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.