Nicolin Chen 7b19a825bd gpu: nvgpu: Remove DMA_NO_KERNEL_MAPPING WAR for coherent chips ...

The commit 3fdd8e38b2 ("gpu: nvgpu: Use our own vmap() for
coherent DMA buffers") added an NVGPU_DMA_NO_KERNEL_MAPPING
flag for coherent chips to work around a memory mapping bug
suspiciously from DMA API.

However, this requires dma-mapping code of ARM64 to support
a legacy DMA_NO_KERNEL_MAPPING attribute for DMA allocation,
which will not likely get upstreamed -- it is not long-term
sustainable. So the plan is to remove this flag from ARM64
part.

The results of 3D benchmarks and GVS sanity tests show that
the system has no regressions in stability, and no mapping
issue being observed after removing this WAR. In case that
GPU code encounters mapping issue in the future, we should
fix from the general DMA API side instead.

Bug 2424160

Change-Id: Ice91f2b2c924beb2f83762cb02efbd53fe7df1c0
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/2001294
Reviewed-by: Konsta Holtta <kholtta@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Alex Waterman <alexw@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

2019-01-28 12:43:47 -08:00

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