drm/xe: Allow num_batch_buffer / num_binds == 0 in IOCTLs

The idea being out-syncs can signal indicating all previous operations
on the bind queue are complete. An example use case of this would be
support for implementing vkQueueWaitIdle easily.

All in-syncs are waited on before signaling out-syncs. This is
implemented by forming a composite software fence of in-syncs and
installing this fence in the out-syncs and exec queue last fence slot.

The last fence must be added as a dependency for jobs on user exec
queues as it is possible for the last fence to be a composite software
fence (unordered, ioctl with zero bb or binds) rather than hardware
fence (ordered, previous job on queue).

Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/drivers/gpu/drm/xe/xe_sched_job.c b/drivers/gpu/drm/xe/xe_sched_job.c
index a9c7ae815bec..01106a1156ad 100644
--- a/drivers/gpu/drm/xe/xe_sched_job.c
+++ b/drivers/gpu/drm/xe/xe_sched_job.c
@@ -260,3 +260,21 @@ void xe_sched_job_push(struct xe_sched_job *job)
 	drm_sched_entity_push_job(&job->drm);
 	xe_sched_job_put(job);
 }
+
+/**
+ * xe_sched_job_last_fence_add_dep - Add last fence dependency to job
+ * @job:job to add the last fence dependency to
+ * @vm: virtual memory job belongs to
+ *
+ * Returns:
+ * 0 on success, or an error on failing to expand the array.
+ */
+int xe_sched_job_last_fence_add_dep(struct xe_sched_job *job, struct xe_vm *vm)
+{
+	struct dma_fence *fence;
+
+	fence = xe_exec_queue_last_fence_get(job->q, vm);
+	dma_fence_get(fence);
+
+	return drm_sched_job_add_dependency(&job->drm, fence);
+}