From 6155186920049693f38856096019c99878cf7f6d Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Thu, 17 Aug 2017 13:37:06 +0100 Subject: [PATCH] drm/i915: Boost GPU clocks if we miss the pageflip's vblank MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit If we miss the current vblank because the gpu was busy, that may cause a jitter as the frame rate temporarily drops. We try to limit the impact of this by then boosting the GPU clock to deliver the frame as quickly as possible. Originally done in commit 808d1ecace30 ("drm/i915: Boost GPU frequency if we detect outstanding pageflips") but was never forward ported to atomic and finally dropped in commit 6d6647463981 ("drm/i915: Rip out legacy page_flip completion/irq handling"). One of the most typical use-cases for this is a mostly idle desktop. Rendering one frame of the desktop's frontbuffer can easily be accomplished by the GPU running at low frequency, but often exceeds the time budget of the desktop compositor. The result is that animations such as opening the menu, doing a fullscreen switch, or even just trying to move a window around are slow and jerky. We need to respond within a frame to give the best impression of a smooth UX, as a compromise we instead respond if that first frame misses its goal. The result should be a near-imperceivable initial delay and a smooth animation even starting from idle. The cost, as ever, is that we spend more power than is strictly necessary as we overestimate the required GPU frequency and then try to ramp down. This of course is reactionary, too little, too late; nevertheless it is surprisingly effective. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=102199 Signed-off-by: Chris Wilson Cc: Maarten Lankhorst Cc: Ville Syrjälä Cc: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20170817123706.6777-1-chris@chris-wilson.co.uk Tested-by: Lyude Paul Reviewed-by: Radoslaw Szwichtenberg --- drivers/gpu/drm/i915/intel_display.c | 62 ++++++++++++++++++++++++++++ drivers/gpu/drm/i915/intel_drv.h | 1 - drivers/gpu/drm/i915/intel_pm.c | 42 ++----------------- 3 files changed, 65 insertions(+), 40 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index 3b95cf9533354..ad74d1d11dbed 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -12636,6 +12636,58 @@ static const struct drm_crtc_funcs intel_crtc_funcs = { .set_crc_source = intel_crtc_set_crc_source, }; +struct wait_rps_boost { + struct wait_queue_entry wait; + + struct drm_crtc *crtc; + struct drm_i915_gem_request *request; +}; + +static int do_rps_boost(struct wait_queue_entry *_wait, + unsigned mode, int sync, void *key) +{ + struct wait_rps_boost *wait = container_of(_wait, typeof(*wait), wait); + struct drm_i915_gem_request *rq = wait->request; + + gen6_rps_boost(rq, NULL); + i915_gem_request_put(rq); + + drm_crtc_vblank_put(wait->crtc); + + list_del(&wait->wait.entry); + kfree(wait); + return 1; +} + +static void add_rps_boost_after_vblank(struct drm_crtc *crtc, + struct dma_fence *fence) +{ + struct wait_rps_boost *wait; + + if (!dma_fence_is_i915(fence)) + return; + + if (INTEL_GEN(to_i915(crtc->dev)) < 6) + return; + + if (drm_crtc_vblank_get(crtc)) + return; + + wait = kmalloc(sizeof(*wait), GFP_KERNEL); + if (!wait) { + drm_crtc_vblank_put(crtc); + return; + } + + wait->request = to_request(dma_fence_get(fence)); + wait->crtc = crtc; + + wait->wait.func = do_rps_boost; + wait->wait.flags = 0; + + add_wait_queue(drm_crtc_vblank_waitqueue(crtc), &wait->wait); +} + /** * intel_prepare_plane_fb - Prepare fb for usage on plane * @plane: drm plane to prepare for @@ -12733,12 +12785,22 @@ intel_prepare_plane_fb(struct drm_plane *plane, return ret; if (!new_state->fence) { /* implicit fencing */ + struct dma_fence *fence; + ret = i915_sw_fence_await_reservation(&intel_state->commit_ready, obj->resv, NULL, false, I915_FENCE_TIMEOUT, GFP_KERNEL); if (ret < 0) return ret; + + fence = reservation_object_get_excl_rcu(obj->resv); + if (fence) { + add_rps_boost_after_vblank(new_state->crtc, fence); + dma_fence_put(fence); + } + } else { + add_rps_boost_after_vblank(new_state->crtc, new_state->fence); } return 0; diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h index 7527ebe8500a8..f60995fe455c5 100644 --- a/drivers/gpu/drm/i915/intel_drv.h +++ b/drivers/gpu/drm/i915/intel_drv.h @@ -1849,7 +1849,6 @@ void gen6_rps_reset_ei(struct drm_i915_private *dev_priv); void gen6_rps_idle(struct drm_i915_private *dev_priv); void gen6_rps_boost(struct drm_i915_gem_request *rq, struct intel_rps_client *rps); -void intel_queue_rps_boost_for_request(struct drm_i915_gem_request *req); void g4x_wm_get_hw_state(struct drm_device *dev); void vlv_wm_get_hw_state(struct drm_device *dev); void ilk_wm_get_hw_state(struct drm_device *dev); diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c index 68187bcfded49..d5ff0b9f999fb 100644 --- a/drivers/gpu/drm/i915/intel_pm.c +++ b/drivers/gpu/drm/i915/intel_pm.c @@ -6169,6 +6169,7 @@ void gen6_rps_boost(struct drm_i915_gem_request *rq, struct intel_rps_client *rps) { struct drm_i915_private *i915 = rq->i915; + unsigned long flags; bool boost; /* This is intentionally racy! We peek at the state here, then @@ -6178,13 +6179,13 @@ void gen6_rps_boost(struct drm_i915_gem_request *rq, return; boost = false; - spin_lock_irq(&rq->lock); + spin_lock_irqsave(&rq->lock, flags); if (!rq->waitboost && !i915_gem_request_completed(rq)) { atomic_inc(&i915->rps.num_waiters); rq->waitboost = true; boost = true; } - spin_unlock_irq(&rq->lock); + spin_unlock_irqrestore(&rq->lock, flags); if (!boost) return; @@ -9155,43 +9156,6 @@ int intel_freq_opcode(struct drm_i915_private *dev_priv, int val) return DIV_ROUND_CLOSEST(val, GT_FREQUENCY_MULTIPLIER); } -struct request_boost { - struct work_struct work; - struct drm_i915_gem_request *req; -}; - -static void __intel_rps_boost_work(struct work_struct *work) -{ - struct request_boost *boost = container_of(work, struct request_boost, work); - struct drm_i915_gem_request *req = boost->req; - - if (!i915_gem_request_completed(req)) - gen6_rps_boost(req, NULL); - - i915_gem_request_put(req); - kfree(boost); -} - -void intel_queue_rps_boost_for_request(struct drm_i915_gem_request *req) -{ - struct request_boost *boost; - - if (req == NULL || INTEL_GEN(req->i915) < 6) - return; - - if (i915_gem_request_completed(req)) - return; - - boost = kmalloc(sizeof(*boost), GFP_ATOMIC); - if (boost == NULL) - return; - - boost->req = i915_gem_request_get(req); - - INIT_WORK(&boost->work, __intel_rps_boost_work); - queue_work(req->i915->wq, &boost->work); -} - void intel_pm_setup(struct drm_i915_private *dev_priv) { mutex_init(&dev_priv->rps.hw_lock); -- 2.39.5