mirror of https://gitee.com/openkylin/linux.git
d1b5e41e13
This adds the driver for the ARM Framebuffer Compression decoders found in the Amlogic GXM and G12A SoCs. The Amlogic GXM and G12A AFBC decoder are totally different, the GXM only handling only the AFBC v1.0 modes and the G12A decoder handling the AFBC v1.2 modes. The G12A AFBC decoder is an external IP integrated in the video pipeline, and the GXM AFBC decoder seems to the an Amlogic custom decoder more tighly integrated in the video pipeline. The GXM AFBC decoder can handle only one AFBC plane for 2 available OSD planes available in HW, and the G12A AFBC decoder can handle up to 4 AFBC planes for up to 3 OSD planes available in HW. The Amlogic GXM supports 16x16 SPARSE and 16x16 SPLIT AFBC buffers up to 4k. On the other side, for G12A SPLIT is mandatory in 16x16 block mode, but for 4k modes 32x8+SPLIT AFBC buffers is manadatory for performances reasons. The RDMA is used here to reset and program the AFBC decoder unit on each vsync without involving the interrupt handler that can be masked for a long period of time, producing display glitches. For this we use the meson_rdma_writel_sync() which adds the register write tuple (VPU register offset and register value) to the RDMA buffer and write the value to the HW. When enabled, the RDMA is enabled to rewrite the same sequence at the next VSYNC event, until a new buffer is committed to the OSD plane. Then the Amlogic G12A is switched to RDMA, the Amlogic GXM Decoder doesn't need a reset/reprogram at each vsync, but needs to keep the vsync interrupt enabled to trigger the RDMA module. Signed-off-by: Neil Armstrong <narmstrong@baylibre.com> Reviewed-by: Kevin Hilman <khilman@baylibre.com> [narmstrong: fixed typo in commit log] Link: https://patchwork.freedesktop.org/patch/msgid/20191021091509.3864-6-narmstrong@baylibre.com |
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| README | ||
README
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.