Re: [PATCH 12/47] drm/i915/guc: Add bypass tasklet submission path to GuC

On 6/24/2021 00:04, Matthew Brost wrote:

Add bypass tasklet submission path to GuC. The tasklet is only used if H2G channel has backpresure.

Signed-off-by: Matthew Brost matthew.brost@intel.com

Reviewed-by: John Harrison John.C.Harrison@Intel.com

---

.../gpu/drm/i915/gt/uc/intel_guc_submission.c | 37 +++++++++++++++---- 1 file changed, 29 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c index ee933efbf0ff..38aff83ee9fa 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c @@ -172,6 +172,12 @@ static int guc_add_request(struct intel_guc *guc, struct i915_request *rq) return err; }

+static inline void guc_set_lrc_tail(struct i915_request *rq) +{

• rq->context->lrc_reg_state[CTX_RING_TAIL] =

• intel_ring_set_tail(rq->ring, rq->tail);
  

+}

• static inline int rq_prio(const struct i915_request *rq) { return rq->sched.attr.priority;

@@ -215,8 +221,7 @@ static int guc_dequeue_one_context(struct intel_guc *guc) } done: if (submit) {

• last->context->lrc_reg_state[CTX_RING_TAIL] =
  

• 	intel_ring_set_tail(last->ring, last->tail);
  

• guc_set_lrc_tail(last);
  

  resubmit: /*
  • We only check for -EBUSY here even though it is possible for

@@ -496,20 +501,36 @@ static inline void queue_request(struct i915_sched_engine *sched_engine, set_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags); }

+static int guc_bypass_tasklet_submit(struct intel_guc *guc,

• 		     struct i915_request *rq)
  

+{

• int ret;
• __i915_request_submit(rq);
• trace_i915_request_in(rq, 0);
• guc_set_lrc_tail(rq);
• ret = guc_add_request(guc, rq);
• if (ret == -EBUSY)

• guc->stalled_request = rq;
  

• return ret;

+}

• static void guc_submit_request(struct i915_request *rq) { struct i915_sched_engine *sched_engine = rq->engine->sched_engine;

• struct intel_guc *guc = &rq->engine->gt->uc.guc; unsigned long flags;

  /* Will be called from irq-context when using foreign fences. */ spin_lock_irqsave(&sched_engine->lock, flags);

• queue_request(sched_engine, rq, rq_prio(rq));
• GEM_BUG_ON(i915_sched_engine_is_empty(sched_engine));
• GEM_BUG_ON(list_empty(&rq->sched.link));
• tasklet_hi_schedule(&sched_engine->tasklet);

• if (guc->stalled_request || !i915_sched_engine_is_empty(sched_engine))

• queue_request(sched_engine, rq, rq_prio(rq));
  

• else if (guc_bypass_tasklet_submit(guc, rq) == -EBUSY)

• tasklet_hi_schedule(&sched_engine->tasklet);
  
  

  spin_unlock_irqrestore(&sched_engine->lock, flags); }