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Commit 4413c474 authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915/execlists: Make submission tasklet hardirq safe 



Prepare to allow the execlists submission to be run from underneath a
hardirq timer context (and not just the current softirq context) as is
required for fast preemption resets and context switches.

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180508210318.10274-1-chris@chris-wilson.co.uk
parent b9777c6f

drivers/gpu/drm/i915/intel_lrc.c

+29 −13
Original line number Diff line number Diff line
@@ -356,10 +356,13 @@ execlists_unwind_incomplete_requests(struct intel_engine_execlists *execlists) 
{

	struct intel_engine_cs *engine =

		container_of(execlists, typeof(*engine), execlists);

	unsigned long flags;



	spin_lock_irqsave(&engine->timeline.lock, flags);



	spin_lock_irq(&engine->timeline.lock);

	__unwind_incomplete_requests(engine);

	spin_unlock_irq(&engine->timeline.lock);



	spin_unlock_irqrestore(&engine->timeline.lock, flags);

}



static inline void
@@ -553,7 +556,7 @@ static void inject_preempt_context(struct intel_engine_cs *engine) 
	execlists_set_active(&engine->execlists, EXECLISTS_ACTIVE_PREEMPT);

}



static void execlists_dequeue(struct intel_engine_cs *engine)

static bool __execlists_dequeue(struct intel_engine_cs *engine)

{

	struct intel_engine_execlists * const execlists = &engine->execlists;

	struct execlist_port *port = execlists->port;
@@ -563,6 +566,8 @@ static void execlists_dequeue(struct intel_engine_cs *engine) 
	struct rb_node *rb;

	bool submit = false;



	lockdep_assert_held(&engine->timeline.lock);



	/* Hardware submission is through 2 ports. Conceptually each port

	 * has a (RING_START, RING_HEAD, RING_TAIL) tuple. RING_START is

	 * static for a context, and unique to each, so we only execute
@@ -584,7 +589,6 @@ static void execlists_dequeue(struct intel_engine_cs *engine) 
	 * and context switches) submission.

	 */



	spin_lock_irq(&engine->timeline.lock);

	rb = execlists->first;

	GEM_BUG_ON(rb_first(&execlists->queue) != rb);
@@ -599,7 +603,7 @@ static void execlists_dequeue(struct intel_engine_cs *engine) 
						EXECLISTS_ACTIVE_USER));

		GEM_BUG_ON(!port_count(&port[0]));

		if (port_count(&port[0]) > 1)

			goto unlock;

			return false;



		/*

		 * If we write to ELSP a second time before the HW has had
@@ -609,11 +613,11 @@ static void execlists_dequeue(struct intel_engine_cs *engine) 
		 * the HW to indicate that it has had a chance to respond.

		 */

		if (!execlists_is_active(execlists, EXECLISTS_ACTIVE_HWACK))

			goto unlock;

			return false;



		if (need_preempt(engine, last, execlists->queue_priority)) {

			inject_preempt_context(engine);

			goto unlock;

			return false;

		}



		/*
@@ -638,7 +642,7 @@ static void execlists_dequeue(struct intel_engine_cs *engine) 
		 * priorities of the ports haven't been switch.

		 */

		if (port_count(&port[1]))

			goto unlock;

			return false;



		/*

		 * WaIdleLiteRestore:bdw,skl
@@ -743,14 +747,26 @@ static void execlists_dequeue(struct intel_engine_cs *engine) 
	/* We must always keep the beast fed if we have work piled up */

	GEM_BUG_ON(execlists->first && !port_isset(execlists->port));



unlock:

	spin_unlock_irq(&engine->timeline.lock);



	if (submit) {

	/* Re-evaluate the executing context setup after each preemptive kick */

	if (last)

		execlists_user_begin(execlists, execlists->port);

		execlists_submit_ports(engine);



	return submit;

}



static void execlists_dequeue(struct intel_engine_cs *engine)

{

	struct intel_engine_execlists * const execlists = &engine->execlists;

	unsigned long flags;

	bool submit;



	spin_lock_irqsave(&engine->timeline.lock, flags);

	submit = __execlists_dequeue(engine);

	spin_unlock_irqrestore(&engine->timeline.lock, flags);



	if (submit)

		execlists_submit_ports(engine);



	GEM_BUG_ON(port_isset(execlists->port) &&

		   !execlists_is_active(execlists, EXECLISTS_ACTIVE_USER));

}