diff --git a/drivers/gpu/drm/panthor/panthor_sched.c b/drivers/gpu/drm/panthor/panthor_sched.c index 79ffcbc41d78..9a0ff48f7061 100644 --- a/drivers/gpu/drm/panthor/panthor_sched.c +++ b/drivers/gpu/drm/panthor/panthor_sched.c @@ -458,6 +458,16 @@ struct panthor_queue { /** @seqno: Sequence number of the last initialized fence. */ atomic64_t seqno; + /** + * @last_fence: Fence of the last submitted job. + * + * We return this fence when we get an empty command stream. + * This way, we are guaranteed that all earlier jobs have completed + * when drm_sched_job::s_fence::finished without having to feed + * the CS ring buffer with a dummy job that only signals the fence. + */ + struct dma_fence *last_fence; + /** * @in_flight_jobs: List containing all in-flight jobs. * @@ -829,6 +839,9 @@ static void group_free_queue(struct panthor_group *group, struct panthor_queue * panthor_kernel_bo_destroy(queue->ringbuf); panthor_kernel_bo_destroy(queue->iface.mem); + /* Release the last_fence we were holding, if any. */ + dma_fence_put(queue->fence_ctx.last_fence); + kfree(queue); } @@ -2784,9 +2797,6 @@ static void group_sync_upd_work(struct work_struct *work) spin_lock(&queue->fence_ctx.lock); list_for_each_entry_safe(job, job_tmp, &queue->fence_ctx.in_flight_jobs, node) { - if (!job->call_info.size) - continue; - if (syncobj->seqno < job->done_fence->seqno) break; @@ -2865,11 +2875,14 @@ queue_run_job(struct drm_sched_job *sched_job) static_assert(sizeof(call_instrs) % 64 == 0, "call_instrs is not aligned on a cacheline"); - /* Stream size is zero, nothing to do => return a NULL fence and let - * drm_sched signal the parent. + /* Stream size is zero, nothing to do except making sure all previously + * submitted jobs are done before we signal the + * drm_sched_job::s_fence::finished fence. */ - if (!job->call_info.size) - return NULL; + if (!job->call_info.size) { + job->done_fence = dma_fence_get(queue->fence_ctx.last_fence); + return dma_fence_get(job->done_fence); + } ret = pm_runtime_resume_and_get(ptdev->base.dev); if (drm_WARN_ON(&ptdev->base, ret)) @@ -2928,6 +2941,10 @@ queue_run_job(struct drm_sched_job *sched_job) } } + /* Update the last fence. */ + dma_fence_put(queue->fence_ctx.last_fence); + queue->fence_ctx.last_fence = dma_fence_get(job->done_fence); + done_fence = dma_fence_get(job->done_fence); out_unlock: @@ -3378,10 +3395,15 @@ panthor_job_create(struct panthor_file *pfile, goto err_put_job; } - job->done_fence = kzalloc(sizeof(*job->done_fence), GFP_KERNEL); - if (!job->done_fence) { - ret = -ENOMEM; - goto err_put_job; + /* Empty command streams don't need a fence, they'll pick the one from + * the previously submitted job. + */ + if (job->call_info.size) { + job->done_fence = kzalloc(sizeof(*job->done_fence), GFP_KERNEL); + if (!job->done_fence) { + ret = -ENOMEM; + goto err_put_job; + } } ret = drm_sched_job_init(&job->base, diff --git a/include/uapi/drm/panthor_drm.h b/include/uapi/drm/panthor_drm.h index aaed8e12ad0b..926b1deb1116 100644 --- a/include/uapi/drm/panthor_drm.h +++ b/include/uapi/drm/panthor_drm.h @@ -802,6 +802,9 @@ struct drm_panthor_queue_submit { * Must be 64-bit/8-byte aligned (the size of a CS instruction) * * Can be zero if stream_addr is zero too. + * + * When the stream size is zero, the queue submit serves as a + * synchronization point. */ __u32 stream_size; @@ -822,6 +825,8 @@ struct drm_panthor_queue_submit { * ensure the GPU doesn't get garbage when reading the indirect command * stream buffers. If you want the cache flush to happen * unconditionally, pass a zero here. + * + * Ignored when stream_size is zero. */ __u32 latest_flush;