Setting this flag on a scheduler fence prevents pipelining of jobs
depending on this fence. In other words we always insert a full CPU
round trip before dependen jobs are pushed to the pipeline.
Signed-off-by: Christian König <christian.koenig@xxxxxxx>
CC: stable@xxxxxxxxxxxxxxx # 5.19+
---
drivers/gpu/drm/scheduler/sched_entity.c | 3 ++-
include/drm/gpu_scheduler.h | 9 +++++++++
2 files changed, 11 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c
index 191c56064f19..43d337d8b153 100644
--- a/drivers/gpu/drm/scheduler/sched_entity.c
+++ b/drivers/gpu/drm/scheduler/sched_entity.c
@@ -385,7 +385,8 @@ static bool drm_sched_entity_add_dependency_cb(struct drm_sched_entity *entity)
}
s_fence = to_drm_sched_fence(fence);
- if (s_fence && s_fence->sched == sched) {
+ if (s_fence && s_fence->sched == sched &&
+ !test_bit(DRM_SCHED_FENCE_DONT_PIPELINE, &fence->flags)) {
/*
* Fence is from the same scheduler, only need to wait for
diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
index 0fca8f38bee4..f01d14b231ed 100644
--- a/include/drm/gpu_scheduler.h
+++ b/include/drm/gpu_scheduler.h
@@ -32,6 +32,15 @@
#define MAX_WAIT_SCHED_ENTITY_Q_EMPTY msecs_to_jiffies(1000)
+/**
+ * DRM_SCHED_FENCE_DONT_PIPELINE - Prefent dependency pipelining
+ *
+ * Setting this flag on a scheduler fence prevents pipelining of jobs depending
+ * on this fence. In other words we always insert a full CPU round trip before
+ * dependen jobs are pushed to the hw queue.
+ */
+#define DRM_SCHED_FENCE_DONT_PIPELINE DMA_FENCE_FLAG_USER_BITS
+
struct drm_gem_object;
struct drm_gpu_scheduler;
--
2.25.1
