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authorAlex Waterman <alexw@nvidia.com>2017-05-25 19:56:50 -0400
committermobile promotions <svcmobile_promotions@nvidia.com>2017-09-22 15:52:48 -0400
commit0090ee5aca268a3c359f34c74b8c521df3bd8593 (patch)
tree2779dc64554cdb38b717ce09c0e3dcbf36107ed3 /drivers/gpu/nvgpu/pmgr/pmgr.c
parente32cc0108cf2ef5de7a17f0f6c0aa9af7faf23ed (diff)
gpu: nvgpu: nvgpu SGL implementation
The last major item preventing the core MM code in the nvgpu driver from being platform agnostic is the usage of Linux scattergather tables and scattergather lists. These data structures are used throughout the mapping code to handle discontiguous DMA allocations and also overloaded to represent VIDMEM allocs. The notion of a scatter gather table is crucial to a HW device that can handle discontiguous DMA. The GPU has a MMU which allows the GPU to do page gathering and present a virtually contiguous buffer to the GPU HW. As a result it makes sense for the GPU driver to use some sort of scatter gather concept so maximize memory usage efficiency. To that end this patch keeps the notion of a scatter gather list but implements it in the nvgpu common code. It is based heavily on the Linux SGL concept. It is a singly linked list of blocks - each representing a chunk of memory. To map or use a DMA allocation SW must iterate over each block in the SGL. This patch implements the most basic level of support for this data structure. There are certainly easy optimizations that could be done to speed up the current implementation. However, this patches' goal is to simply divest the core MM code from any last Linux'isms. Speed and efficiency come next. Change-Id: Icf44641db22d87fa1d003debbd9f71b605258e42 Signed-off-by: Alex Waterman <alexw@nvidia.com> Reviewed-on: https://git-master.nvidia.com/r/1530867 Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com> Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>
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