drm/amd/display: Flush ISM work before releasing the stream

[Why]
ISM timers are not tied to the atomic commit, so a timer armed before a
DPMS off can still fire after the stream is released. The external display
check in dcn35_apply_idle_power_optimizations() loops over the active
streams, so with none left it never runs and idle is allowed on an
external-only system.

[How]
Wait out pending and in-flight ISM work before dc_stream_release(); dc_lock
is not held there, so the sync wait is safe. Rename amdgpu_dm_ism_fini() to
amdgpu_dm_ism_flush() and assert dc_lock is not held.

Assisted-by: Cursor:Claude-Opus-5
Reviewed-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Ray Wu <ray.wu@amd.com>
Signed-off-by: Chenyu Chen <chen-yu.chen@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

5 files changed, 72 insertions, 47 deletions

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index c5c728085113..9761fdf4ea11 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -4615,6 +4615,13 @@ static void amdgpu_dm_commit_streams(struct drm_atomic_commit *state,
 		    (!new_crtc_state->active ||
 		     drm_atomic_crtc_needs_modeset(new_crtc_state))) {
 			manage_dm_interrupts(adev, acrtc, NULL);
+			/*
+			 * ISM hysteresis lives on system_dfl_wq, not the
+			 * vblank workqueue. Wait it out so a timer armed while
+			 * the stream existed cannot allow idle after the
+			 * stream is released.
+			 */
+			amdgpu_dm_ism_flush(&acrtc->ism);
 			dc_stream_release(dm_old_crtc_state->stream);
 		}
 	}
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crtc.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crtc.c
index 4b8530d734e5..a7979b418c2b 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crtc.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crtc.c
@@ -480,9 +480,9 @@ EXPORT_IF_KUNIT(amdgpu_dm_crtc_duplicate_state);
 STATIC_IFN_KUNIT void amdgpu_dm_crtc_destroy(struct drm_crtc *crtc)
 {
 	/*
-	 * amdgpu_dm_ism_fini() is intentionally called in amdgpu_dm_fini().
-	 * It must be called before dc_destroy() in amdgpu_dm_fini()
-	 * to avoid ISM accessing an invalid dc handle once dc is released.
+	 * ISM workers are intentionally quiesced by amdgpu_dm_ism_disable()
+	 * in amdgpu_dm_fini(). That must happen before dc_destroy() so ISM
+	 * cannot access an invalid dc handle once dc is released.
 	 */
 
 	drm_crtc_cleanup(crtc);
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_ism.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_ism.c
index 4e57572e12b6..127eaba4de60 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_ism.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_ism.c
@@ -647,9 +647,26 @@ void amdgpu_dm_ism_init(struct amdgpu_dm_ism *ism,
 EXPORT_IF_KUNIT(amdgpu_dm_ism_init);
 
 
-void amdgpu_dm_ism_fini(struct amdgpu_dm_ism *ism)
+/**
+ * amdgpu_dm_ism_flush - Cancel any pending, or wait out in-flight ISM work
+ *
+ * @ism: The CRTC's idle state manager
+ *
+ * Cancels the hysteresis and SSO timers and waits for a running worker to
+ * finish. Callers that are about to drop the CRTC's stream use this so that a
+ * timer armed while the stream was still around cannot allow idle afterwards.
+ *
+ * Must not be called with dc_lock held: the workers take dc_lock themselves,
+ * so waiting for them under it would deadlock.
+ */
+void amdgpu_dm_ism_flush(struct amdgpu_dm_ism *ism)
 {
+	struct amdgpu_crtc *acrtc = ism_to_amdgpu_crtc(ism);
+	struct amdgpu_device *adev = drm_to_adev(acrtc->base.dev);
+
+	lockdep_assert_not_held(&adev->dm.dc_lock);
+
 	cancel_delayed_work_sync(&ism->sso_delayed_work);
 	cancel_delayed_work_sync(&ism->delayed_work);
 }
-EXPORT_IF_KUNIT(amdgpu_dm_ism_fini);
+EXPORT_IF_KUNIT(amdgpu_dm_ism_flush);
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_ism.h b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_ism.h
index afce16f7085a..893e062bb281 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_ism.h
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_ism.h
@@ -142,7 +142,7 @@ struct amdgpu_dm_ism {
 
 void amdgpu_dm_ism_init(struct amdgpu_dm_ism *ism,
 			struct amdgpu_dm_ism_config *config);
-void amdgpu_dm_ism_fini(struct amdgpu_dm_ism *ism);
+void amdgpu_dm_ism_flush(struct amdgpu_dm_ism *ism);
 void amdgpu_dm_ism_commit_event(struct amdgpu_dm_ism *ism,
 				enum amdgpu_dm_ism_event event);
 void amdgpu_dm_ism_disable(struct amdgpu_display_manager *dm);
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/tests/amdgpu_dm_ism_test.c b/drivers/gpu/drm/amd/display/amdgpu_dm/tests/amdgpu_dm_ism_test.c
index b77df47d3095..a9c6485e2a9e 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/tests/amdgpu_dm_ism_test.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/tests/amdgpu_dm_ism_test.c
@@ -642,31 +642,6 @@ static void dm_test_ism_init_sets_initial_state(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, ism->config.sso_num_frames, config.sso_num_frames);
 }
 
-/* ===== Tests for amdgpu_dm_ism_fini ===== */
-
-/**
- * dm_test_ism_fini_after_init - fini cancels never-scheduled work without error
- * @test: KUnit test context
- */
-static void dm_test_ism_fini_after_init(struct kunit *test)
-{
-	struct amdgpu_dm_ism *ism = alloc_test_ism(test);
-	struct amdgpu_dm_ism_config config = {
-		.filter_num_frames = 5,
-		.filter_entry_count = 3,
-		.activation_num_delay_frames = 10,
-		.sso_num_frames = 2,
-	};
-
-	amdgpu_dm_ism_init(ism, &config);
-	/* Work was never scheduled; cancel_delayed_work_sync is a no-op. */
-	amdgpu_dm_ism_fini(ism);
-
-	/* FSM state is untouched by fini */
-	KUNIT_EXPECT_EQ(test, (int)ism->current_state,
-			(int)DM_ISM_STATE_FULL_POWER_RUNNING);
-}
-
 /* ===== Tests for dm_ism_set_last_idle_ts ===== */
 
 /**
@@ -897,6 +872,32 @@ static void register_test_acrtc(struct amdgpu_device *adev,
 	list_add_tail(&acrtc->base.head, &adev->ddev.mode_config.crtc_list);
 }
 
+/* ===== Tests for amdgpu_dm_ism_flush ===== */
+
+/**
+ * dm_test_ism_flush_after_init - flush cancels never-scheduled work without error
+ * @test: KUnit test context
+ */
+static void dm_test_ism_flush_after_init(struct kunit *test)
+{
+	struct amdgpu_crtc *acrtc = alloc_test_acrtc(test, NULL);
+	struct amdgpu_dm_ism *ism = &acrtc->ism;
+	struct amdgpu_dm_ism_config config = {
+		.filter_num_frames = 5,
+		.filter_entry_count = 3,
+		.activation_num_delay_frames = 10,
+		.sso_num_frames = 2,
+	};
+
+	amdgpu_dm_ism_init(ism, &config);
+	/* Work was never scheduled; cancel_delayed_work_sync is a no-op. */
+	amdgpu_dm_ism_flush(ism);
+
+	/* FSM state is untouched by flush */
+	KUNIT_EXPECT_EQ(test, (int)ism->current_state,
+			(int)DM_ISM_STATE_FULL_POWER_RUNNING);
+}
+
 /* ===== Tests for amdgpu_dm_ism_commit_event ===== */
 
 /**
@@ -922,7 +923,7 @@ static void dm_test_ism_commit_event_no_state(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, (int)acrtc->ism.current_state,
 			(int)DM_ISM_STATE_FULL_POWER_RUNNING);
 
-	amdgpu_dm_ism_fini(&acrtc->ism);
+	amdgpu_dm_ism_flush(&acrtc->ism);
 }
 
 /**
@@ -958,7 +959,7 @@ static void dm_test_ism_commit_event_cursor_transition(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, (int)acrtc->ism.current_state,
 			(int)DM_ISM_STATE_FULL_POWER_RUNNING);
 
-	amdgpu_dm_ism_fini(&acrtc->ism);
+	amdgpu_dm_ism_flush(&acrtc->ism);
 }
 
 /**
@@ -988,7 +989,7 @@ static void dm_test_ism_commit_event_invalid_event(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, (int)acrtc->ism.current_state,
 			(int)DM_ISM_STATE_FULL_POWER_RUNNING);
 
-	amdgpu_dm_ism_fini(&acrtc->ism);
+	amdgpu_dm_ism_flush(&acrtc->ism);
 }
 
 /* ===== Tests for amdgpu_dm_ism_force_full_power ===== */
@@ -1020,7 +1021,7 @@ static void dm_test_ism_force_full_power(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, (int)acrtc->ism.current_state,
 			(int)DM_ISM_STATE_FULL_POWER_RUNNING);
 
-	amdgpu_dm_ism_fini(&acrtc->ism);
+	amdgpu_dm_ism_flush(&acrtc->ism);
 }
 
 /* ===== Tests for amdgpu_dm_ism_disable / amdgpu_dm_ism_enable ===== */
@@ -1048,7 +1049,7 @@ static void dm_test_ism_disable_enable_cycle(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, (int)acrtc->ism.current_state,
 			(int)DM_ISM_STATE_FULL_POWER_RUNNING);
 
-	amdgpu_dm_ism_fini(&acrtc->ism);
+	amdgpu_dm_ism_flush(&acrtc->ism);
 }
 
 /* ===== Tests for dm_ism_dispatch_power_state (via commit_event) ===== */
@@ -1127,7 +1128,7 @@ static void dm_test_ism_dispatch_hysteresis_schedule_and_cancel(struct kunit *te
 				(int)DM_ISM_STATE_HYSTERESIS_BUSY);
 	}
 
-	amdgpu_dm_ism_fini(&acrtc->ism);
+	amdgpu_dm_ism_flush(&acrtc->ism);
 }
 
 /**
@@ -1183,7 +1184,7 @@ static void dm_test_ism_dispatch_optimized_idle_defers_sso(struct kunit *test)
 		cancel_delayed_work(&acrtc->ism.sso_delayed_work);
 	}
 
-	amdgpu_dm_ism_fini(&acrtc->ism);
+	amdgpu_dm_ism_flush(&acrtc->ism);
 }
 
 /*
@@ -1285,7 +1286,7 @@ static void dm_test_ism_commit_allows_idle_on_optimized_idle(struct kunit *test)
 		cancel_delayed_work(&acrtc->ism.sso_delayed_work);
 	}
 
-	amdgpu_dm_ism_fini(&acrtc->ism);
+	amdgpu_dm_ism_flush(&acrtc->ism);
 }
 
 /**
@@ -1322,7 +1323,7 @@ static void dm_test_ism_commit_enables_sso_on_optimized_idle_sso(struct kunit *t
 		KUNIT_EXPECT_TRUE(test, adev->dm.dc->idle_optimizations_allowed);
 	}
 
-	amdgpu_dm_ism_fini(&acrtc->ism);
+	amdgpu_dm_ism_flush(&acrtc->ism);
 }
 
 /**
@@ -1371,7 +1372,7 @@ static void dm_test_ism_commit_disallows_idle_on_timer_aborted(struct kunit *tes
 		KUNIT_EXPECT_FALSE(test, adev->dm.dc->idle_optimizations_allowed);
 	}
 
-	amdgpu_dm_ism_fini(&acrtc->ism);
+	amdgpu_dm_ism_flush(&acrtc->ism);
 }
 
 /**
@@ -1413,7 +1414,7 @@ static void dm_test_ism_exit_from_optimized_idle_disallows_idle(struct kunit *te
 		KUNIT_EXPECT_EQ(test, acrtc->ism.next_record_idx, 1);
 	}
 
-	amdgpu_dm_ism_fini(&acrtc->ism);
+	amdgpu_dm_ism_flush(&acrtc->ism);
 }
 
 /**
@@ -1452,7 +1453,7 @@ static void dm_test_ism_exit_from_sso_disallows_idle(struct kunit *test)
 		KUNIT_EXPECT_EQ(test, acrtc->ism.next_record_idx, 1);
 	}
 
-	amdgpu_dm_ism_fini(&acrtc->ism);
+	amdgpu_dm_ism_flush(&acrtc->ism);
 }
 
 /**
@@ -1496,7 +1497,7 @@ static void dm_test_ism_delayed_work_runs_timer_elapsed(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, dm_ism_test_idle.calls, 1);
 	KUNIT_EXPECT_TRUE(test, adev->dm.dc->idle_optimizations_allowed);
 
-	amdgpu_dm_ism_fini(&acrtc->ism);
+	amdgpu_dm_ism_flush(&acrtc->ism);
 }
 
 /**
@@ -1534,7 +1535,7 @@ static void dm_test_ism_sso_delayed_work_runs_sso_elapsed(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, dm_ism_test_idle.calls, 3);
 	KUNIT_EXPECT_TRUE(test, adev->dm.dc->idle_optimizations_allowed);
 
-	amdgpu_dm_ism_fini(&acrtc->ism);
+	amdgpu_dm_ism_flush(&acrtc->ism);
 }
 
 static struct kunit_case dm_ism_test_cases[] = {
@@ -1582,8 +1583,8 @@ static struct kunit_case dm_ism_test_cases[] = {
 	KUNIT_CASE(dm_test_ism_idle_delay_entry_count_exceeds_history_size),
 	/* amdgpu_dm_ism_init */
 	KUNIT_CASE(dm_test_ism_init_sets_initial_state),
-	/* amdgpu_dm_ism_fini */
-	KUNIT_CASE(dm_test_ism_fini_after_init),
+	/* amdgpu_dm_ism_flush */
+	KUNIT_CASE(dm_test_ism_flush_after_init),
 	/* dm_ism_set_last_idle_ts */
 	KUNIT_CASE(dm_test_ism_set_last_idle_ts_updates_timestamp),
 	/* dm_ism_insert_record */