gpu: nvgpu: Implement compbits mapping

Implement NVGPU_AS_IOCTL_GET_BUFFER_COMPBITS_INFO for requesting info
on compbits-mappable buffers; and NVGPU_AS_IOCTL_MAP_BUFFER_COMPBITS,
which enables mapping compbits to the GPU address space of said
buffers. This, subsequently, enables moving comptag swizzling from GPU
to CDEH/CDEV formats to userspace.

Compbits mapping is conservative and it may map more than what is
strictly needed. This is because two reasons: 1) mapping must be done
on small page alignment (4kB), and 2) GPU comptags are swizzled all
around the aggregate cache line, which means that the whole cache line
must be visible even if only some comptag lines are required from
it. Cache line size is not necessarily a multiple of the small page
size.

Bug 200077571

Change-Id: I5ae88fe6b616e5ea37d3bff0dff46c07e9c9267e
Signed-off-by: Sami Kiminki <skiminki@nvidia.com>
Reviewed-on: http://git-master/r/719710
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
Tested-by: Terje Bergstrom <tbergstrom@nvidia.com>

0 files changed, 0 insertions, 0 deletions