linux-stable.git/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_ism.h, branch v7.2 Linux kernel stable tree drm/amd/display: Extract dm_ism_dispatch_next_event 2026-06-03T17:41:44+00:00 Alex Hung alex.hung@amd.com 2026-05-15T19:27:56+00:00 f84c48048b491941af8caaa65d4260123cab7257 [Why & How] Separate the "should we emit IMMEDIATE?" decision into a pure, side-effect-free helper so it can be tested in isolation without a full DRM context. - dm_ism_dispatch_next_event(current_state, delay_ns, sso_delay_ns) returns DM_ISM_EVENT_IMMEDIATE when the state requires an immediate follow-up (HYSTERESIS_WAITING with zero delay, OPTIMIZED_IDLE with zero SSO delay, or TIMER_ABORTED), and DM_ISM_NUM_EVENTS otherwise. - Removes the passthrough event parameter that was always DM_ISM_NUM_EVENTS at the call site, making the sentinel explicit. - Drops the now-unused event parameter from dm_ism_dispatch_power_state. Assisted-by: Copilot:Claude-Sonnet-4.6 Reviewed-by: Ray Wu <ray.wu@amd.com> Signed-off-by: Alex Hung <alex.hung@amd.com> Signed-off-by: Ray Wu <ray.wu@amd.com> Tested-by: Daniel Wheeler <daniel.wheeler@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com> 
[Why & How]
Separate the "should we emit IMMEDIATE?" decision into a pure,
side-effect-free helper so it can be tested in isolation without a
full DRM context.

- dm_ism_dispatch_next_event(current_state, delay_ns, sso_delay_ns)
  returns DM_ISM_EVENT_IMMEDIATE when the state requires an immediate
  follow-up (HYSTERESIS_WAITING with zero delay, OPTIMIZED_IDLE with
  zero SSO delay, or TIMER_ABORTED), and DM_ISM_NUM_EVENTS otherwise.

- Removes the passthrough event parameter that was always
  DM_ISM_NUM_EVENTS at the call site, making the sentinel explicit.

- Drops the now-unused event parameter from dm_ism_dispatch_power_state.

Assisted-by: Copilot:Claude-Sonnet-4.6
Reviewed-by: Ray Wu <ray.wu@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Ray Wu <ray.wu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
drm/amd/display: Add more KUnit tests for amdgpu_dm_ism 2026-06-03T17:41:38+00:00 Alex Hung alex.hung@amd.com 2026-05-15T15:55:45+00:00 a3142b13fe9fdbc3738026cc1cfeb7b2ab38a382 [Why & How] Add 8 more KUnit tests: - dm_ism_get_idle_allow_delay: add a case where filter_entry_count exceeds filter_history_size, exercising the max() branch in the history_size calculation. - amdgpu_dm_ism_init: verify all fields are initialised to expected values after construction. - amdgpu_dm_ism_fini: smoke-test cancellation of never-scheduled delayed work items paired with a preceding init. - dm_ism_set_last_idle_ts: verify last_idle_timestamp_ns is updated to at least the value captured before the call. - dm_ism_insert_record: verify index increment and duration calculation; verify out-of-bounds index wraps to slot 0. - dm_ism_trigger_event: verify current_state and previous_state are updated on a valid transition and left unchanged on an invalid one. Assisted-by: Copilot:Claude-Sonnet-4.6 Reviewed-by: Ray Wu <ray.wu@amd.com> Signed-off-by: Alex Hung <alex.hung@amd.com> Signed-off-by: Ray Wu <ray.wu@amd.com> Tested-by: Daniel Wheeler <daniel.wheeler@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com> 
[Why & How]
Add 8 more KUnit tests:

- dm_ism_get_idle_allow_delay: add a case where filter_entry_count
  exceeds filter_history_size, exercising the max() branch in the
  history_size calculation.
- amdgpu_dm_ism_init: verify all fields are initialised to
  expected values after construction.
- amdgpu_dm_ism_fini: smoke-test cancellation of never-scheduled
  delayed work items paired with a preceding init.
- dm_ism_set_last_idle_ts: verify last_idle_timestamp_ns is
  updated to at least the value captured before the call.
- dm_ism_insert_record: verify index increment and duration
  calculation; verify out-of-bounds index wraps to slot 0.
- dm_ism_trigger_event: verify current_state and previous_state
  are updated on a valid transition and left unchanged on an
  invalid one.

Assisted-by: Copilot:Claude-Sonnet-4.6
Reviewed-by: Ray Wu <ray.wu@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Ray Wu <ray.wu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
drm/amd/display: Add KUnit test for ISM functions 2026-05-19T15:54:37+00:00 Alex Hung alex.hung@amd.com 2026-04-23T20:12:36+00:00 5838a89515c87c072057c12cf022f958ece1c720 Add KUnit tests for three static functions in amdgpu_dm_ism.c: dm_ism_next_state, dm_ism_get_sso_delay, and dm_ism_get_idle_allow_delay. The 32 test cases cover the full FSM transition table, SSO delay calculation with various timings, and hysteresis-based idle allow delay including circular buffer wraparound and old history cutoff logic. Conditionally remove static linkage and export the three functions under CONFIG_DRM_AMD_DC_KUNIT_TEST so the test module can call them. Assisted-by: Copilot:Claude-Opus-4.6 Reviewed-by: Harry Wentland <harry.wentland@amd.com> Signed-off-by: Alex Hung <alex.hung@amd.com> Signed-off-by: Ivan Lipski <ivan.lipski@amd.com> Tested-by: Dan Wheeler <daniel.wheeler@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com> 
Add KUnit tests for three static functions in amdgpu_dm_ism.c:
dm_ism_next_state, dm_ism_get_sso_delay, and
dm_ism_get_idle_allow_delay.

The 32 test cases cover the full FSM transition table,
SSO delay calculation with various timings, and
hysteresis-based idle allow delay including circular
buffer wraparound and old history cutoff logic.

Conditionally remove static linkage and export the three
functions under CONFIG_DRM_AMD_DC_KUNIT_TEST so the test
module can call them.

Assisted-by: Copilot:Claude-Opus-4.6
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Ivan Lipski <ivan.lipski@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
drm/amd/display: Fix ISM dc_lock deadlock during suspend 2026-05-19T15:45:40+00:00 Ray Wu ray.wu@amd.com 2026-04-30T02:08:16+00:00 3714fe242592e3699ac5e2c19d68b275a210be7d [Why] System hang observed during suspend/resume while video is playing. amdgpu_dm_ism_disable() is called under dc_lock and waits for ISM delayed work via disable_delayed_work_sync(). The work handlers themselves take dc_lock, producing an ABBA deadlock when a worker is in flight at suspend time. [How] Split the disable path into two phases with opposite locking contracts: 1. amdgpu_dm_ism_disable() -- quiesces workers, must NOT hold dc_lock. 2. amdgpu_dm_ism_force_full_power() (new) -- drives the ISM FSM back to FULL_POWER_RUNNING, must hold dc_lock. Reviewed-by: Sun peng (Leo) Li <sunpeng.li@amd.com> Signed-off-by: Ray Wu <ray.wu@amd.com> Signed-off-by: Ivan Lipski <ivan.lipski@amd.com> Tested-by: Dan Wheeler <daniel.wheeler@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com> 
[Why]
System hang observed during suspend/resume while video is playing.
amdgpu_dm_ism_disable() is called under dc_lock and waits for ISM
delayed work via disable_delayed_work_sync(). The work handlers
themselves take dc_lock, producing an ABBA deadlock when a worker is
in flight at suspend time.

[How]
Split the disable path into two phases with opposite locking
contracts:
  1. amdgpu_dm_ism_disable() -- quiesces workers, must NOT hold
     dc_lock.
  2. amdgpu_dm_ism_force_full_power() (new) -- drives the ISM FSM
     back to FULL_POWER_RUNNING, must hold dc_lock.

Reviewed-by: Sun peng (Leo) Li <sunpeng.li@amd.com>
Signed-off-by: Ray Wu <ray.wu@amd.com>
Signed-off-by: Ivan Lipski <ivan.lipski@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
drm/amd/display: Add Idle state manager(ISM) 2026-03-30T19:14:05+00:00 Ray Wu ray.wu@amd.com 2025-12-17T08:36:02+00:00 754003486c3cc95f2fcb9d6b71a779047d6db95c [Why] Rapid allow/disallow of idle optimization calls, whether it be IPS or self-refresh features, can end up using more power if actual time-in-idle is low. It can also spam DMUB command submission in a way that prevents it from servicing other requestors. [How] Introduce the Idle State Manager (ISM) to amdgpu. It maintains a finite state machine that uses a hysteresis to determine if a delay should be inserted between a caller allowing idle, and when the actual idle optimizations are programmed. A second timer is also introduced to enable static screen optimizations (SSO) such as PSR1 and Replay low HZ idle mode. Rapid SSO enable/disable can have a negative power impact on some low hz video playback, and can introduce user lag for PSR1 (due to up to 3 frames of sync latency). This effectively rate-limits idle optimizations, based on hysteresis. This also replaces the existing delay logic used for PSR1, allowing drm_vblank_crtc_config.disable_immediate = true, and thus allowing drm_crtc_vblank_restore(). v2: * Loosen criteria for ISM to exit idle optimizations; it failed to exit idle correctly on cursor updates when there are no drm_vblank requestors, * Document default_ism_config * Convert pr_debug to trace events to reduce overhead on frequent codepaths * checkpatch.pl fixes Link: https://gitlab.freedesktop.org/drm/amd/-/issues/4527 Link: https://gitlab.freedesktop.org/drm/amd/-/issues/3709 Fixes: 58a261bfc967 ("drm/amd/display: use a more lax vblank enable policy for older ASICs") Signed-off-by: Ray Wu <ray.wu@amd.com> Signed-off-by: Leo Li <sunpeng.li@amd.com> Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org> Signed-off-by: Alex Deucher <alexander.deucher@amd.com> 
[Why]

Rapid allow/disallow of idle optimization calls, whether it be IPS or
self-refresh features, can end up using more power if actual
time-in-idle is low. It can also spam DMUB command submission in a way
that prevents it from servicing other requestors.

[How]

Introduce the Idle State Manager (ISM) to amdgpu. It maintains a finite
state machine that uses a hysteresis to determine if a delay should be
inserted between a caller allowing idle, and when the actual idle
optimizations are programmed.

A second timer is also introduced to enable static screen optimizations
(SSO) such as PSR1 and Replay low HZ idle mode. Rapid SSO enable/disable
can have a negative power impact on some low hz video playback, and can
introduce user lag for PSR1 (due to up to 3 frames of sync latency).

This effectively rate-limits idle optimizations, based on hysteresis.

This also replaces the existing delay logic used for PSR1, allowing
drm_vblank_crtc_config.disable_immediate = true, and thus allowing
drm_crtc_vblank_restore().

v2:
* Loosen criteria for ISM to exit idle optimizations; it failed to exit
  idle correctly on cursor updates when there are no drm_vblank
  requestors,
* Document default_ism_config
* Convert pr_debug to trace events to reduce overhead on frequent
  codepaths
* checkpatch.pl fixes

Link: https://gitlab.freedesktop.org/drm/amd/-/issues/4527
Link: https://gitlab.freedesktop.org/drm/amd/-/issues/3709
Fixes: 58a261bfc967 ("drm/amd/display: use a more lax vblank enable policy for older ASICs")
Signed-off-by: Ray Wu <ray.wu@amd.com>
Signed-off-by: Leo Li <sunpeng.li@amd.com>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>