[PATCH v10 0/9] drm: Add DRM_MODE_ATOMIC_RESET flag

[Maxime Ripard <mripard@kernel.org>]

Hi,

Userspace currently has no atomic way to bring a display pipeline back
to a pristine state. A compositor that wants to start from a known
baseline must explicitly set every property on every KMS object to its
default value, which requires tracking which properties exist and what
their defaults are. This is fragile and must be updated every time a
new property is added to the kernel.

This series introduces a new DRM_MODE_ATOMIC_RESET flag for the
atomic ioctl. When set, the kernel fills the commit with default
states for all KMS objects before applying the properties supplied in
the request. Properties not explicitly included remain at their
defaults. This allows userspace to describe the desired end state
declaratively, without caring about the current state or the full set
of properties.

A driver-specific property is added to vkms planes for testing.
Standard properties are impractical for this: compositors like Mutter
enumerate all known properties, making it hard to isolate the reset
behavior in a test.

Mutter has a working implementation using the new flag, with a
vkms-based test exercising the reset behavior:
https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/5309

And we have IGT tests as well:
https://lore.kernel.org/r/20261112162147.766264-1-mripard@kernel.org/

Let me know what you think,
Maxime

Signed-off-by: Maxime Ripard <mripard@kernel.org>
---
Changes in v10:
- Stop trying to make partial lease work, they aren't meant to exist, so
  we can simply error out when they happen
- More tests for zpos and color management
- Fix DPU1 issues reported by sashiko
- Link to v9: https://lore.kernel.org/r/20261110-drm-reset-state-flag-v9-0-ddb0e26324a0@kernel.org

Changes in v9:
- Add a flag to know if leases have been revoked or are empty
- Handle the situation where a leased plane or connector being reset
  would disable an unleased CRTC
- Add more kunit tests to cover the new issues reported by sashiko
- Fix reset-related bugs in amdgpu, vc4 and msm DPU
- Add a vc4 kunit test for its reset related bug
- Link to v8: https://lore.kernel.org/r/20261106-drm-reset-state-flag-v8-0-50fd046b705f@kernel.org

Changes in v8:
- Fix more leases issues
- Drop applied patches
- Link to v7: https://lore.kernel.org/r/20261030-drm-reset-state-flag-v7-0-4e55eaeae683@kernel.org

Changes in v7:
- Fix a whole bunch of sashiko issues to deal with color_mgmt_changed,
  leases, partially leased devices (like a plane leased but it's crtc
  isn't) and the interaction with PAGE_FLIP_EVENT better
- Fix crtc create_state implementation for ssd130x
- Actually make it possible for a compositor to recreate the same whole
  state without passing ALLOW_MODESET
- Fix EDEADLK bugs with kunit tests
- Don't report DRM_CAP_ATOMIC_RESET on !atomic drivers
- Fix error handling in vkms for the new property
- Add more kunit tests for the new corner cases
- Link to v6: https://lore.kernel.org/r/20261022-drm-reset-state-flag-v6-0-f36d640b7e76@kernel.org

Changes in v6:
- If using a lease, only considered the leased objects
- Fix amdgpu plane atomic_create_state implementation
- Link to v5: https://lore.kernel.org/r/20261016-drm-reset-state-flag-v5-0-dad2d64b693b@kernel.org

Changes in v5:
- Fix bisection issue
- Improve the documentation
- Fix connector hotplugging issue
- Added kunit tests for drm_atomic_commit_fill_with_defaults()
- Link to v4: https://lore.kernel.org/r/20260918-drm-reset-state-flag-v4-0-5ad106370f05@kernel.org

Changes in v4:
- Improve the drm_atomic_get_private_obj_state and
  drm_atomic_get_connector_state array reallocations
- Return void on functions to insert an object state into a commit when
  it cannot fail
- Rename drm_atomic_can_create_state() into
  drm_atomic_implements_create_state()
- Move capability check from drm_atomic_commit_fill_with_defaults to its
  caller 
- Added IGT test
- Link to v3: https://lore.kernel.org/r/20260908-drm-reset-state-flag-v3-0-905570f387a4@kernel.org

Changes in v3:
- Rebased on top of the latest atomic_create_state series
- Sebastian Wick created and tested this work with mutter and vkms
- Fix colorop locking
- Link to v2: https://lore.kernel.org/r/20260812-drm-reset-state-flag-v2-0-e96ce13317dd@kernel.org

Changes in v2:
- Fix bisection
- Add capability to let userspace know if it can reset the state
- Link to v1: https://lore.kernel.org/r/20260708-drm-reset-state-flag-v1-0-c37dc985485d@kernel.org

---
Maxime Ripard (8):
      drm/amd/display: Fix planes atomic_create_state implementation
      drm/atomic: Add drm_atomic_implements_create_state() helper
      drm/atomic: Allow filling a commit with pristine object states
      drm/tests: atomic: Add tests for drm_atomic_commit_fill_with_defaults()
      drm/amd/display: Take over the current stream and dc_state
      drm/vc4: Carry the HVS channel over to created CRTC states
      drm/msm/dpu1: Carry the mixers over to created CRTC states
      drm/vkms: Add driver-specific plane property for testing

Sebastian Wick (1):
      drm/atomic-uapi: Add DRM_MODE_ATOMIC_RESET flag

 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c  |  50 +++
 .../drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c    |   3 -
 drivers/gpu/drm/drm_atomic.c                       | 337 ++++++++++++++++
 drivers/gpu/drm/drm_atomic_uapi.c                  |  44 ++-
 drivers/gpu/drm/drm_ioctl.c                        |   5 +
 drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c           |  23 ++
 drivers/gpu/drm/tests/drm_atomic_test.c            | 435 ++++++++++++++++++++-
 drivers/gpu/drm/vc4/tests/vc4_test_pv_muxing.c     | 105 +++++
 drivers/gpu/drm/vc4/vc4_kms.c                      |  16 +-
 drivers/gpu/drm/vkms/vkms_drv.h                    |   3 +
 drivers/gpu/drm/vkms/vkms_plane.c                  |  63 ++-
 include/drm/drm_atomic.h                           |   4 +
 include/uapi/drm/drm.h                             |  10 +
 include/uapi/drm/drm_mode.h                        |  22 +-
 14 files changed, 1107 insertions(+), 13 deletions(-)
---
base-commit: d2a8cee91bfa8616f713c7c8f539a81e8e3554ea
change-id: 20260708-drm-reset-state-flag-2fb2b5711f97

Best regards,
-- 
Maxime Ripard <mripard@kernel.org>