Re: [PATCH 6/7] drm/i915: Boost GPU frequency if we detect outstanding pageflips

[Deepak S <deepak.s@linux.intel.com>]

On Wednesday 18 March 2015 01:48 PM, Deepak S wrote:
>
>
> On Friday 06 March 2015 08:36 PM, Chris Wilson wrote:
>> If we hit a vblank and see that have a pageflip queue but not yet
>> processed, ensure that the GPU is running at maximum in order to clear
>> the backlog. Pageflips are only queued for the following vblank, if we
>> miss it, there will be a visible stutter. Boosting the GPU frequency
>> doesn't prevent us from missing the target vblank, but it should help
>> the subsequent frames hitting theirs.
>>
>> v2: Reorder vblank vs flip-complete so that we only check for a missed
>> flip after processing the completion events, and avoid spurious boosts.
>>
>> v3: Rename missed_vblank
>> v4: Rebase
>> v5: Cancel the outstanding work in runtime suspend
>> v6: Rebase
>>
>> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
>> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
>> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
>> ---
>>   drivers/gpu/drm/i915/intel_display.c | 11 ++++++++---
>>   drivers/gpu/drm/i915/intel_drv.h     |  2 ++
>>   drivers/gpu/drm/i915/intel_pm.c      | 34 
>> ++++++++++++++++++++++++++++++++++
>>   3 files changed, 44 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_display.c 
>> b/drivers/gpu/drm/i915/intel_display.c
>> index 2412002d510b..7735f0a4184c 100644
>> --- a/drivers/gpu/drm/i915/intel_display.c
>> +++ b/drivers/gpu/drm/i915/intel_display.c
>> @@ -9818,6 +9818,7 @@ void intel_check_page_flip(struct drm_device 
>> *dev, int pipe)
>>       struct drm_i915_private *dev_priv = dev->dev_private;
>>       struct drm_crtc *crtc = dev_priv->pipe_to_crtc_mapping[pipe];
>>       struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
>> +    struct intel_unpin_work *work;
>>         WARN_ON(!in_irq());
>>   @@ -9825,12 +9826,16 @@ void intel_check_page_flip(struct 
>> drm_device *dev, int pipe)
>>           return;
>>         spin_lock(&dev->event_lock);
>> -    if (intel_crtc->unpin_work && __intel_pageflip_stall_check(dev, 
>> crtc)) {
>> +    work = intel_crtc->unpin_work;
>> +    if (work != NULL && __intel_pageflip_stall_check(dev, crtc)) {
>>           WARN_ONCE(1, "Kicking stuck page flip: queued at %d, now 
>> %d\n",
>> -             intel_crtc->unpin_work->flip_queued_vblank,
>> -             drm_vblank_count(dev, pipe));
>> +             work->flip_queued_vblank, drm_vblank_count(dev, pipe));
>>           page_flip_completed(intel_crtc);
>> +        work = NULL;
>>       }
>> +    if (work != NULL &&
>> +        drm_vblank_count(dev, pipe) - work->flip_queued_vblank > 1)
>> +        intel_queue_rps_boost_for_request(dev, work->flip_queued_req);
>>       spin_unlock(&dev->event_lock);
>>   }
>>   diff --git a/drivers/gpu/drm/i915/intel_drv.h 
>> b/drivers/gpu/drm/i915/intel_drv.h
>> index 1e564da2fd38..87e09a58191a 100644
>> --- a/drivers/gpu/drm/i915/intel_drv.h
>> +++ b/drivers/gpu/drm/i915/intel_drv.h
>> @@ -1242,6 +1242,8 @@ void gen6_rps_busy(struct drm_i915_private 
>> *dev_priv);
>>   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_private *dev_priv);
>> +void intel_queue_rps_boost_for_request(struct drm_device *dev,
>> +                       struct drm_i915_gem_request *rq);
>>   void ilk_wm_get_hw_state(struct drm_device *dev);
>>   void skl_wm_get_hw_state(struct drm_device *dev);
>>   void skl_ddb_get_hw_state(struct drm_i915_private *dev_priv,
>> diff --git a/drivers/gpu/drm/i915/intel_pm.c 
>> b/drivers/gpu/drm/i915/intel_pm.c
>> index 972333d2211d..120b8af3c60c 100644
>> --- a/drivers/gpu/drm/i915/intel_pm.c
>> +++ b/drivers/gpu/drm/i915/intel_pm.c
>> @@ -6598,6 +6598,40 @@ int intel_freq_opcode(struct drm_i915_private 
>> *dev_priv, int val)
>>           return val / GT_FREQUENCY_MULTIPLIER;
>>   }
>>   +struct request_boost {
>> +    struct work_struct work;
>> +    struct drm_i915_gem_request *rq;
>> +};
>> +
>> +static void __intel_rps_boost_work(struct work_struct *work)
>> +{
>> +    struct request_boost *boost = container_of(work, struct 
>> request_boost, work);
>> +
>> +    if (!i915_gem_request_completed(boost->rq, true))
>> +        gen6_rps_boost(to_i915(boost->rq->ring->dev));
>> +
>> +    i915_gem_request_unreference(boost->rq);
>> +    kfree(boost);
>> +}
>> +
>> +void intel_queue_rps_boost_for_request(struct drm_device *dev,
>> +                       struct drm_i915_gem_request *rq)
>> +{
>> +    struct request_boost *boost;
>> +
>> +    if (rq == NULL || INTEL_INFO(dev)->gen < 6)
>> +        return;
>> +
>> +    boost = kmalloc(sizeof(*boost), GFP_ATOMIC);
>> +    if (boost == NULL)
>> +        return;
>> +
>> +    INIT_WORK(&boost->work, __intel_rps_boost_work);
>> +    i915_gem_request_assign(&boost->rq, rq);
>> +
>> +    queue_work(to_i915(dev)->wq, &boost->work);
>> +}
>> +
>>   void intel_pm_setup(struct drm_device *dev)
>>   {
>>        struct drm_i915_private *dev_priv = dev->dev_private;

Patch looks fine
Reviewed-by: Deepak S<deepak.s@linux.intel.com>

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