[PATCH v3 0/5] drm/i915: Allow user to set cache at BO creation

Fri Apr 28 16:00:31 UTC 2023

On 4/28/23 17:19, Yang, Fei wrote:
> > On 4/28/23 07:47, fei.yang at intel.com wrote:
> >> From: Fei Yang <fei.yang at intel.com>
> >>
> >> The first three patches in this series are taken from
> >> https://patchwork.freedesktop.org/series/116868/
> >> These patches are included here because the last patch
> >> has dependency on the pat_index refactor.
> >>
> >> This series is focusing on uAPI changes,
> >> 1. end support for set caching ioctl [PATCH 4/5]
> >> 2. add set_pat extension for gem_create [PATCH 5/5]
> >>
> >> v2: drop one patch that was merged separately
> >>      341ad0e8e254 drm/i915/mtl: Add PTE encode function
> >> v3: rebase on https://patchwork.freedesktop.org/series/117082/
> >
> > Hi, Fei.
> >
> > Does this uAPI update also affect any discrete GPUs supported by i915,
>
> It does.
>
> > And in that case, does it allow setting non-snooping PAT indices on
> > those devices?
>
> It allows setting PAT indices specified in
> KMD does a sanity check so that it won't go over the max recommended
> by bspec.
>
> > If so, since the uAPI for discrete GPU devices doesn't allow incoherency
> > between GPU and CPU (apart from write-combining buffering), the correct
> > CPU caching mode matching the PAT index needs to be selected for the
> > buffer object in i915_ttm_select_tt_caching().
>
> The patch doesn't affect the CPU caching mode setting logic though.
> And the caching settings for objects created by kernel should remain
> the same for both CPU and GPU, objects created by userspace are
> managed completely by userspace.
>
> One question though, what do you mean by non-snooping PAT indices?
> The PAT index registers don't really control coherency mode in the past,
> I believe MTL is the first one that has COH_MODE in the PAT registers.
> Aren't discrete GPUs snooping CPU cache automatically?

Yes, that was actually the bottom question: What do these PAT settings 
allow you to do WRT the snooping on supported discrete devices (DG2) on 
i915?

If they indeed don't allow disabling snooping, then that's not a 
problem. If they do, the ttm code there needs some modification.

Thanks,

Thomas

>
> -Fei
>
> > Thanks,
> > Thomas
> >
> >>
> >> Fei Yang (5):
> >>    drm/i915: preparation for using PAT index
> >>    drm/i915: use pat_index instead of cache_level
> >>    drm/i915: make sure correct pte encode is used
> >>    drm/i915/mtl: end support for set caching ioctl
> >>    drm/i915: Allow user to set cache at BO creation
> >>
> >> drivers/gpu/drm/i915/display/intel_dpt.c      | 12 +--
> >> drivers/gpu/drm/i915/gem/i915_gem_create.c    | 36 +++++++++
> >> drivers/gpu/drm/i915/gem/i915_gem_domain.c    | 46 ++++++-----
> >> .../gpu/drm/i915/gem/i915_gem_execbuffer.c    | 10 ++-
> >> drivers/gpu/drm/i915/gem/i915_gem_mman.c      |  3 +-
> >> drivers/gpu/drm/i915/gem/i915_gem_object.c    | 67 +++++++++++++++-
> >> drivers/gpu/drm/i915/gem/i915_gem_object.h    |  8 ++
> >> .../gpu/drm/i915/gem/i915_gem_object_types.h  | 26 +++++-
> >> drivers/gpu/drm/i915/gem/i915_gem_shmem.c     |  9 ++-
> >> drivers/gpu/drm/i915/gem/i915_gem_shrinker.c  |  2 -
> >> drivers/gpu/drm/i915/gem/i915_gem_stolen.c    |  4 +-
> >> drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c  | 16 ++--
> >> .../gpu/drm/i915/gem/selftests/huge_pages.c   |  2 +-
> >> .../drm/i915/gem/selftests/i915_gem_migrate.c |  2 +-
> >> .../drm/i915/gem/selftests/i915_gem_mman.c    |  2 +-
> >> drivers/gpu/drm/i915/gt/gen6_ppgtt.c          | 10 ++-
> >> drivers/gpu/drm/i915/gt/gen8_ppgtt.c          | 73 +++++++++--------
> >> drivers/gpu/drm/i915/gt/gen8_ppgtt.h          |  3 +-
> >> drivers/gpu/drm/i915/gt/intel_ggtt.c          | 76 +++++++++---------
> >> drivers/gpu/drm/i915/gt/intel_gtt.h           | 20 +++--
> >>   drivers/gpu/drm/i915/gt/intel_migrate.c       | 47 ++++++-----
> >> drivers/gpu/drm/i915/gt/intel_migrate.h       | 13 ++-
> >> drivers/gpu/drm/i915/gt/intel_ppgtt.c         |  6 +-
> >> drivers/gpu/drm/i915/gt/selftest_migrate.c    | 47 +++++------
> >> drivers/gpu/drm/i915/gt/selftest_reset.c      |  8 +-
> >> drivers/gpu/drm/i915/gt/selftest_timeline.c   |  2 +-
> >> drivers/gpu/drm/i915/gt/selftest_tlb.c        |  4 +-
> >> drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c      | 10 ++-
> >> drivers/gpu/drm/i915/i915_debugfs.c           | 55 ++++++++++---
> >> drivers/gpu/drm/i915/i915_gem.c               | 16 +++-
> >> drivers/gpu/drm/i915/i915_gpu_error.c         |  8 +-
> >> drivers/gpu/drm/i915/i915_pci.c               | 79 ++++++++++++++++---
> >> drivers/gpu/drm/i915/i915_vma.c               | 16 ++--
> >> drivers/gpu/drm/i915/i915_vma.h               |  2 +-
> >> drivers/gpu/drm/i915/i915_vma_types.h         |  2 -
> >> drivers/gpu/drm/i915/intel_device_info.h      |  5 ++
> >> drivers/gpu/drm/i915/selftests/i915_gem.c     |  5 +-
> >> .../gpu/drm/i915/selftests/i915_gem_evict.c   |  4 +-
> >> drivers/gpu/drm/i915/selftests/i915_gem_gtt.c | 15 ++--
> >> .../drm/i915/selftests/intel_memory_region.c  |  4 +-
> >> .../gpu/drm/i915/selftests/mock_gem_device.c  |  9 +++
> >> drivers/gpu/drm/i915/selftests/mock_gtt.c     |  8 +-
> >> include/uapi/drm/i915_drm.h                   | 36 +++++++++
> >> tools/include/uapi/drm/i915_drm.h             | 36 +++++++++
> >>   44 files changed, 621 insertions(+), 243 deletions(-)
> >>
>
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