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Commit dcff85c8 authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915: Enable i915_gem_wait_for_idle() without holding struct_mutex 



The principal motivation for this was to try and eliminate the
struct_mutex from i915_gem_suspend - but we still need to hold the mutex
current for the i915_gem_context_lost(). (The issue there is that there
may be an indirect lockdep cycle between cpu_hotplug (i.e. suspend) and
struct_mutex via the stop_machine().) For the moment, enabling last
request tracking for the engine, allows us to do busyness checking and
waiting without requiring the struct_mutex - which is useful in its own
right.

As a side-effect of having a robust means for tracking engine busyness,
we can replace our other busyness heuristic, that of comparing against
the last submitted seqno. For paranoid reasons, we have a semi-ordered
check of that seqno inside the hangchecker, which we can now improve to
an ordered check of the engine's busyness (removing a locked xchg in the
process).

v2: Pass along "bool interruptible" as being unlocked we cannot rely on
i915->mm.interruptible being stable or even under our control.
v3: Replace check Ironlake i915_gpu_busy() with the common precalculated value

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470388464-28458-6-git-send-email-chris@chris-wilson.co.uk
parent 90f4fcd5

drivers/gpu/drm/i915/i915_debugfs.c

+1 −1
Original line number Diff line number Diff line
@@ -4925,7 +4925,7 @@ i915_drop_caches_set(void *data, u64 val) 
		return ret;



	if (val & DROP_ACTIVE) {

		ret = i915_gem_wait_for_idle(dev_priv);

		ret = i915_gem_wait_for_idle(dev_priv, true);

		if (ret)

			goto unlock;

	}

drivers/gpu/drm/i915/i915_drv.h

+2 −1
Original line number Diff line number Diff line
@@ -3233,7 +3233,8 @@ int __must_check i915_gem_init(struct drm_device *dev); 
int __must_check i915_gem_init_hw(struct drm_device *dev);

void i915_gem_init_swizzling(struct drm_device *dev);

void i915_gem_cleanup_engines(struct drm_device *dev);

int __must_check i915_gem_wait_for_idle(struct drm_i915_private *dev_priv);

int __must_check i915_gem_wait_for_idle(struct drm_i915_private *dev_priv,

					bool interruptible);

int __must_check i915_gem_suspend(struct drm_device *dev);

void i915_gem_resume(struct drm_device *dev);

int i915_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf);

drivers/gpu/drm/i915/i915_gem.c

+14 −17
Original line number Diff line number Diff line
@@ -2438,13 +2438,18 @@ static void i915_gem_reset_engine_status(struct intel_engine_cs *engine) 


static void i915_gem_reset_engine_cleanup(struct intel_engine_cs *engine)

{

	struct drm_i915_gem_request *request;

	struct intel_ring *ring;



	request = i915_gem_active_peek(&engine->last_request,

				       &engine->i915->drm.struct_mutex);



	/* Mark all pending requests as complete so that any concurrent

	 * (lockless) lookup doesn't try and wait upon the request as we

	 * reset it.

	 */

	intel_engine_init_seqno(engine, engine->last_submitted_seqno);

	if (request)

		intel_engine_init_seqno(engine, request->fence.seqno);



	/*

	 * Clear the execlists queue up before freeing the requests, as those
@@ -2466,15 +2471,9 @@ static void i915_gem_reset_engine_cleanup(struct intel_engine_cs *engine) 
	 * implicit references on things like e.g. ppgtt address spaces through

	 * the request.

	 */

	if (!list_empty(&engine->request_list)) {

		struct drm_i915_gem_request *request;



		request = list_last_entry(&engine->request_list,

					  struct drm_i915_gem_request,

					  link);



	if (request)

		i915_gem_request_retire_upto(request);

	}

	GEM_BUG_ON(intel_engine_is_active(engine));



	/* Having flushed all requests from all queues, we know that all

	 * ringbuffers must now be empty. However, since we do not reclaim
@@ -2897,18 +2896,17 @@ int i915_vma_unbind(struct i915_vma *vma) 
	return 0;

}



int i915_gem_wait_for_idle(struct drm_i915_private *dev_priv)

int i915_gem_wait_for_idle(struct drm_i915_private *dev_priv,

			   bool interruptible)

{

	struct intel_engine_cs *engine;

	int ret;



	lockdep_assert_held(&dev_priv->drm.struct_mutex);



	for_each_engine(engine, dev_priv) {

		if (engine->last_context == NULL)

			continue;



		ret = intel_engine_idle(engine);

		ret = intel_engine_idle(engine, interruptible);

		if (ret)

			return ret;

	}
@@ -4080,11 +4078,10 @@ struct i915_vma *i915_gem_obj_to_ggtt_view(struct drm_i915_gem_object *obj, 
	return NULL;

}



int

i915_gem_suspend(struct drm_device *dev)

int i915_gem_suspend(struct drm_device *dev)

{

	struct drm_i915_private *dev_priv = to_i915(dev);

	int ret = 0;

	int ret;



	intel_suspend_gt_powersave(dev_priv);
@@ -4102,7 +4099,7 @@ i915_gem_suspend(struct drm_device *dev) 
	if (ret)

		goto err;



	ret = i915_gem_wait_for_idle(dev_priv);

	ret = i915_gem_wait_for_idle(dev_priv, true);

	if (ret)

		goto err;

drivers/gpu/drm/i915/i915_gem_evict.c

+3 −3
Original line number Diff line number Diff line
@@ -39,7 +39,7 @@ gpu_is_idle(struct drm_i915_private *dev_priv) 
	struct intel_engine_cs *engine;



	for_each_engine(engine, dev_priv) {

		if (!list_empty(&engine->request_list))

		if (intel_engine_is_active(engine))

			return false;

	}
@@ -167,7 +167,7 @@ i915_gem_evict_something(struct i915_address_space *vm, 
	if (ret)

		return ret;



	ret = i915_gem_wait_for_idle(dev_priv);

	ret = i915_gem_wait_for_idle(dev_priv, true);

	if (ret)

		return ret;
@@ -272,7 +272,7 @@ int i915_gem_evict_vm(struct i915_address_space *vm, bool do_idle) 
				return ret;

		}



		ret = i915_gem_wait_for_idle(dev_priv);

		ret = i915_gem_wait_for_idle(dev_priv, true);

		if (ret)

			return ret;

drivers/gpu/drm/i915/i915_gem_gtt.c

+1 −1
Original line number Diff line number Diff line
@@ -2248,7 +2248,7 @@ static bool do_idling(struct drm_i915_private *dev_priv) 


	if (unlikely(ggtt->do_idle_maps)) {

		dev_priv->mm.interruptible = false;

		if (i915_gem_wait_for_idle(dev_priv)) {

		if (i915_gem_wait_for_idle(dev_priv, false)) {

			DRM_ERROR("Failed to wait for idle; VT'd may hang.\n");

			/* Wait a bit, in hopes it avoids the hang */

			udelay(10);