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From patchwork Thu Aug 17 12:37:06 2017
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Subject: drm/i915: Boost GPU clocks if we miss the pageflip's vblank
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From: Chris Wilson <chris@chris-wilson.co.uk>
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X-Patchwork-Id: 172204
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Message-Id: <20170817123706.6777-1-chris@chris-wilson.co.uk>
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To: intel-gfx@lists.freedesktop.org
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Cc: Daniel Vetter <daniel.vetter@intel.com>
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Date: Thu, 17 Aug 2017 13:37:06 +0100
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If we miss the current vblank because the gpu was busy, that may cause a
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jitter as the frame rate temporarily drops. We try to limit the impact
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of this by then boosting the GPU clock to deliver the frame as quickly
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as possible. Originally done in commit 6ad790c0f5ac ("drm/i915: Boost GPU
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frequency if we detect outstanding pageflips") but was never forward
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ported to atomic and finally dropped in commit fd3a40242e87 ("drm/i915:
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Rip out legacy page_flip completion/irq handling").
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References: https://bugs.freedesktop.org/show_bug.cgi?id=102199
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Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
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Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
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Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
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Cc: Daniel Vetter <daniel.vetter@intel.com>
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Tested-by: Lyude Paul <lyude@redhat.com>
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Reviewed-by: Radoslaw Szwichtenberg <radoslaw.szwichtenberg@intel.com>
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---
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 drivers/gpu/drm/i915/intel_display.c | 59 ++++++++++++++++++++++++++++++++++++
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 drivers/gpu/drm/i915/intel_drv.h     |  1 -
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 drivers/gpu/drm/i915/intel_pm.c      | 42 ++-----------------------
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 3 files changed, 62 insertions(+), 40 deletions(-)
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diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
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index 0e93ec201fe3..7d5b19553637 100644
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--- a/drivers/gpu/drm/i915/intel_display.c
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+++ b/drivers/gpu/drm/i915/intel_display.c
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@@ -12636,6 +12636,55 @@ static const struct drm_crtc_funcs intel_crtc_funcs = {
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 	.set_crc_source = intel_crtc_set_crc_source,
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 };
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+struct wait_rps_boost {
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+	struct wait_queue_entry wait;
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+
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+	struct drm_crtc *crtc;
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+	struct drm_i915_gem_request *request;
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+};
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+
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+static int do_rps_boost(struct wait_queue_entry *_wait,
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+			unsigned mode, int sync, void *key)
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+{
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+	struct wait_rps_boost *wait = container_of(_wait, typeof(*wait), wait);
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+	struct drm_i915_gem_request *rq = wait->request;
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+
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+	gen6_rps_boost(rq, NULL);
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+	i915_gem_request_put(rq);
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+
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+	drm_crtc_vblank_put(wait->crtc);
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+
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+	list_del(&wait->wait.entry);
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+	kfree(wait);
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+	return 1;
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+}
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+
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+static void add_rps_boost_after_vblank(struct drm_crtc *crtc,
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+				       struct dma_fence *fence)
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+{
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+	struct wait_rps_boost *wait;
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+
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+	if (!dma_fence_is_i915(fence))
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+		return;
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+
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+	if (drm_crtc_vblank_get(crtc))
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+		return;
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+
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+	wait = kmalloc(sizeof(*wait), GFP_KERNEL);
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+	if (!wait) {
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+		drm_crtc_vblank_put(crtc);
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+		return;
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+	}
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+
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+	wait->request = to_request(dma_fence_get(fence));
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+	wait->crtc = crtc;
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+
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+	wait->wait.func = do_rps_boost;
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+	wait->wait.flags = 0;
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+
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+	add_wait_queue(drm_crtc_vblank_waitqueue(crtc), &wait->wait);
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+}
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+
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 /**
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  * intel_prepare_plane_fb - Prepare fb for usage on plane
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  * @plane: drm plane to prepare for
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@@ -12733,12 +12782,22 @@ intel_prepare_plane_fb(struct drm_plane *plane,
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 		return ret;
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 	if (!new_state->fence) { /* implicit fencing */
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+		struct dma_fence *fence;
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+
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 		ret = i915_sw_fence_await_reservation(&intel_state->commit_ready,
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 						      obj->resv, NULL,
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 						      false, I915_FENCE_TIMEOUT,
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 						      GFP_KERNEL);
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 		if (ret < 0)
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 			return ret;
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+
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+		fence = reservation_object_get_excl_rcu(obj->resv);
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+		if (fence) {
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+			add_rps_boost_after_vblank(new_state->crtc, fence);
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+			dma_fence_put(fence);
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+		}
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+	} else {
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+		add_rps_boost_after_vblank(new_state->crtc, new_state->fence);
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 	}
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 	return 0;
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diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
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index fa47285918f4..e092354b4d63 100644
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--- a/drivers/gpu/drm/i915/intel_drv.h
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+++ b/drivers/gpu/drm/i915/intel_drv.h
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@@ -1844,7 +1844,6 @@ void gen6_rps_reset_ei(struct drm_i915_private *dev_priv);
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 void gen6_rps_idle(struct drm_i915_private *dev_priv);
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 void gen6_rps_boost(struct drm_i915_gem_request *rq,
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 		    struct intel_rps_client *rps);
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-void intel_queue_rps_boost_for_request(struct drm_i915_gem_request *req);
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 void g4x_wm_get_hw_state(struct drm_device *dev);
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 void vlv_wm_get_hw_state(struct drm_device *dev);
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 void ilk_wm_get_hw_state(struct drm_device *dev);
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diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
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index ed662937ec3c..c9fa2eb1903c 100644
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--- a/drivers/gpu/drm/i915/intel_pm.c
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+++ b/drivers/gpu/drm/i915/intel_pm.c
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@@ -6169,6 +6169,7 @@ void gen6_rps_boost(struct drm_i915_gem_request *rq,
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 		    struct intel_rps_client *rps)
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 {
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 	struct drm_i915_private *i915 = rq->i915;
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+	unsigned long flags;
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 	bool boost;
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 	/* This is intentionally racy! We peek at the state here, then
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@@ -6178,13 +6179,13 @@ void gen6_rps_boost(struct drm_i915_gem_request *rq,
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 		return;
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 	boost = false;
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-	spin_lock_irq(&rq->lock);
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+	spin_lock_irqsave(&rq->lock, flags);
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 	if (!rq->waitboost && !i915_gem_request_completed(rq)) {
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 		atomic_inc(&i915->rps.num_waiters);
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 		rq->waitboost = true;
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 		boost = true;
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 	}
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-	spin_unlock_irq(&rq->lock);
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+	spin_unlock_irqrestore(&rq->lock, flags);
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 	if (!boost)
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 		return;
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@@ -9132,43 +9133,6 @@ int intel_freq_opcode(struct drm_i915_private *dev_priv, int val)
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 		return DIV_ROUND_CLOSEST(val, GT_FREQUENCY_MULTIPLIER);
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 }
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-struct request_boost {
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-	struct work_struct work;
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-	struct drm_i915_gem_request *req;
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-};
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-
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-static void __intel_rps_boost_work(struct work_struct *work)
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-{
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-	struct request_boost *boost = container_of(work, struct request_boost, work);
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-	struct drm_i915_gem_request *req = boost->req;
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-
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-	if (!i915_gem_request_completed(req))
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-		gen6_rps_boost(req, NULL);
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-
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-	i915_gem_request_put(req);
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-	kfree(boost);
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-}
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-
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-void intel_queue_rps_boost_for_request(struct drm_i915_gem_request *req)
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-{
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-	struct request_boost *boost;
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-
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-	if (req == NULL || INTEL_GEN(req->i915) < 6)
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-		return;
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-
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-	if (i915_gem_request_completed(req))
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-		return;
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-
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-	boost = kmalloc(sizeof(*boost), GFP_ATOMIC);
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-	if (boost == NULL)
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-		return;
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-
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-	boost->req = i915_gem_request_get(req);
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-
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-	INIT_WORK(&boost->work, __intel_rps_boost_work);
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-	queue_work(req->i915->wq, &boost->work);
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-}
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-
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 void intel_pm_setup(struct drm_i915_private *dev_priv)
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 {
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 	mutex_init(&dev_priv->rps.hw_lock);