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

Das, Nirmoy
2022-03-02T15:32:37Z

Reviewed-by: Nirmoy Das <nirmoy.das@intel.com> for the series as well.

On 01/03/2022 22:53, Ramalingam C wrote:
> 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(-)
>