[PATCH v5 1/4] drm/amdgpu: Signal USERQ_EOP EVENTFD notifications

Signal USERQ_EOP EVENTFD subscriptions from the USERQ interrupt path.

The EOP interrupt already identifies the queue that completed. Use the
queue object directly to notify matching EVENTFD subscribers.

Routing notifications through the queue object keeps delivery tied to
the queue instance that generated the completion event, avoiding
ambiguities from reused queue identifiers or doorbell indices.

EVENTFD remains notification-only and carries no event payload.

v2: (per Christian)
- Move USERQ_EOP EVENTFD signaling into amdgpu_userq_process_fence_irq().
- Reuse the existing doorbell-to-queue lookup instead of duplicating it
  in the interrupt handler.
- Keep fence processing and EVENTFD notification handling together in a
  single helper.

Cc: Alex Deucher <[email protected]>
Cc: Christian König <[email protected]>
Signed-off-by: Srinivasan Shanmugam <[email protected]>
Reviewed-by: Alex Deucher <[email protected]>
Reviewed-by: Christian König <[email protected]>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
index fbf783946f6d..ab3ef3a9f655 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
@@ -215,6 +215,7 @@ void amdgpu_userq_process_fence_irq(struct amdgpu_device *adev, u32 doorbell)
 {
 	struct xarray *xa = &adev->userq_doorbell_xa;
 	struct amdgpu_usermode_queue *queue;
+	struct amdgpu_eventfd_mgr *eventfd_mgr;
 	unsigned long flags;
 	int r;
 
@@ -232,6 +233,11 @@ void amdgpu_userq_process_fence_irq(struct amdgpu_device *adev, u32 doorbell)
 		/* Restart the timer when there are still fences pending */
 		if (r == 1)
 			amdgpu_userq_start_hang_detect_work(queue);
+
+		eventfd_mgr = amdgpu_userq_eventfd_mgr(queue->userq_mgr);
+		amdgpu_eventfd_signal(eventfd_mgr,
+				      DRM_AMDGPU_EVENT_TYPE_USERQ_EOP,
+				      queue);
 	}
 	xa_unlock_irqrestore(xa, flags);
 }
-- 
2.34.1