[Intel-gfx] [PATCH v2 0/4] drm/i915/ttm: Evict and store of compressed object

Ramalingam C
2022-03-01T21:53:16Z

On Xe-HP and later devices, we use dedicated compression control
state (CCS) stored in local memory for each surface, to support
the 3D and media compression formats.

The memory required for the CCS of the entire local memory is
1/256 of the local memory size. So before the kernel
boot, the required memory is reserved for the CCS data and a
secure register will be programmed with the CCS base address

So when we allocate a object in local memory we dont need to explicitly
allocate the space for ccs data. But when we evict the obj into the smem
to hold the compression related data along with the obj we need smem
space of obj_size + (obj_size/256).

Hence when we create smem for an obj with lmem placement possibility we
create with the extra space.

When we are swapping out the local memory obj on flat-ccs capable platform,
we need to capture the ccs data too along with main meory and we need to
restore it when we are swapping in the content.

When lmem object is swapped into a smem obj, smem obj will
have the extra pages required to hold the ccs data corresponding to the
lmem main memory. So main memory of lmem will be copied into the initial
pages of the smem and then ccs data corresponding to the main memory
will be copied to the subsequent pages of smem.

Swapin happens exactly in reverse order. First main memory of lmem is
restored from the smem's initial pages and the ccs data will be restored
from the subsequent pages of smem.

Extracting and restoring the CCS data is done through a special cmd called
XY_CTRL_SURF_COPY_BLT

Test-with: 20220301212513.30772-1-ramalingam.c@intel.com

Ayaz A Siddiqui (1):
drm/i915/gt: Clear compress metadata for Xe_HP platforms

Ramalingam C (3):
drm/ttm: parameter to add extra pages into ttm_tt
drm/i915/gem: Extra pages in ttm_tt for ccs data
drm/i915/migrate: Evict and restore the flatccs capable lmem obj

drivers/gpu/drm/drm_gem_vram_helper.c | 2 +-
drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 23 +-
drivers/gpu/drm/i915/gt/intel_gpu_commands.h | 15 +
drivers/gpu/drm/i915/gt/intel_migrate.c | 327 +++++++++++++++++--
drivers/gpu/drm/qxl/qxl_ttm.c | 2 +-
drivers/gpu/drm/ttm/ttm_agp_backend.c | 2 +-
drivers/gpu/drm/ttm/ttm_tt.c | 12 +-
drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c | 2 +-
include/drm/ttm/ttm_tt.h | 4 +-
9 files changed, 357 insertions(+), 32 deletions(-)

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2.20.1