Re: [PATCH 2.9/5] drm/i915: Do not wait for flips in intel_crtc_disable_noatomic.

[Ander Conselvan De Oliveira <conselvan2@gmail.com>]

On Mon, 2015-10-19 at 17:09 +0200, Maarten Lankhorst wrote:
> Op 19-10-15 om 15:16 schreef Ander Conselvan De Oliveira:
> > On Wed, 2015-09-23 at 13:27 +0200, Maarten Lankhorst wrote:
> > > Move it from intel_crtc_atomic_commit to prepare_plane_fb.
> > > Waiting is done before committing, otherwise it's too late
> > > to undo the changes.
> > > 
> > > Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/intel_atomic.c  |   2 -
> > >  drivers/gpu/drm/i915/intel_display.c | 107 ++++++++++++++++++++----------
> > > ----
> > > -
> > >  drivers/gpu/drm/i915/intel_drv.h     |   2 -
> > >  3 files changed, 62 insertions(+), 49 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/intel_atomic.c
> > > b/drivers/gpu/drm/i915/intel_atomic.c
> > > index f1975f267710..25a891aa3824 100644
> > > --- a/drivers/gpu/drm/i915/intel_atomic.c
> > > +++ b/drivers/gpu/drm/i915/intel_atomic.c
> > > @@ -205,8 +205,6 @@ int intel_atomic_setup_scalers(struct drm_device *dev,
> > >  				 * but since this plane is unchanged just
> > > do
> > > the
> > >  				 * minimum required validation.
> > >  				 */
> > > -				if (plane->type ==
> > > DRM_PLANE_TYPE_PRIMARY)
> > > -					intel_crtc->atomic.wait_for_flips
> > > =
> > > true;
> > >  				crtc_state->base.planes_changed = true;
> > >  			}
> > >  
> > > diff --git a/drivers/gpu/drm/i915/intel_display.c
> > > b/drivers/gpu/drm/i915/intel_display.c
> > > index 25e1eac260fd..cd651ff6c15b 100644
> > > --- a/drivers/gpu/drm/i915/intel_display.c
> > > +++ b/drivers/gpu/drm/i915/intel_display.c
> > > @@ -3221,32 +3221,6 @@ void intel_finish_reset(struct drm_device *dev)
> > >  	drm_modeset_unlock_all(dev);
> > >  }
> > >  
> > > -static void
> > > -intel_finish_fb(struct drm_framebuffer *old_fb)
> > > -{
> > > -	struct drm_i915_gem_object *obj = intel_fb_obj(old_fb);
> > > -	struct drm_i915_private *dev_priv = to_i915(obj->base.dev);
> > > -	bool was_interruptible = dev_priv->mm.interruptible;
> > > -	int ret;
> > > -
> > > -	/* Big Hammer, we also need to ensure that any pending
> > > -	 * MI_WAIT_FOR_EVENT inside a user batch buffer on the
> > > -	 * current scanout is retired before unpinning the old
> > > -	 * framebuffer. Note that we rely on userspace rendering
> > > -	 * into the buffer attached to the pipe they are waiting
> > > -	 * on. If not, userspace generates a GPU hang with IPEHR
> > > -	 * point to the MI_WAIT_FOR_EVENT.
> > > -	 *
> > > -	 * This should only fail upon a hung GPU, in which case we
> > > -	 * can safely continue.
> > > -	 */
> > > -	dev_priv->mm.interruptible = false;
> > > -	ret = i915_gem_object_wait_rendering(obj, true);
> > > -	dev_priv->mm.interruptible = was_interruptible;
> > > -
> > > -	WARN_ON(ret);
> > > -}
> > > -
> > >  static bool intel_crtc_has_pending_flip(struct drm_crtc *crtc)
> > >  {
> > >  	struct drm_device *dev = crtc->dev;
> > > @@ -3867,15 +3841,23 @@ static void page_flip_completed(struct intel_crtc
> > > *intel_crtc)
> > >  				 work->pending_flip_obj);
> > >  }
> > >  
> > > -void intel_crtc_wait_for_pending_flips(struct drm_crtc *crtc)
> > > +static int intel_crtc_wait_for_pending_flips(struct drm_crtc *crtc)
> > >  {
> > >  	struct drm_device *dev = crtc->dev;
> > >  	struct drm_i915_private *dev_priv = dev->dev_private;
> > > +	long ret;
> > >  
> > >  	WARN_ON(waitqueue_active(&dev_priv->pending_flip_queue));
> > > -	if (WARN_ON(wait_event_timeout(dev_priv->pending_flip_queue,
> > > -				      
> > >  !intel_crtc_has_pending_flip(crtc),
> > > -				       60*HZ) == 0)) {
> > > +
> > > +	ret = wait_event_interruptible_timeout(
> > > +					dev_priv->pending_flip_queue,
> > > +					!intel_crtc_has_pending_flip(crtc
> > > ),
> > > +					60*HZ);
> > > +
> > > +	if (ret < 0)
> > > +		return ret;
> > > +
> > > +	if (ret == 0) {
> > >  		struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
> > >  
> > >  		spin_lock_irq(&dev->event_lock);
> > > @@ -3886,11 +3868,7 @@ void intel_crtc_wait_for_pending_flips(struct
> > > drm_crtc
> > > *crtc)
> > >  		spin_unlock_irq(&dev->event_lock);
> > >  	}
> > >  
> > > -	if (crtc->primary->fb) {
> > > -		mutex_lock(&dev->struct_mutex);
> > > -		intel_finish_fb(crtc->primary->fb);
> > > -		mutex_unlock(&dev->struct_mutex);
> > > -	}
> > There is another caller of intel_crtc_wait_for_pending_flips() besides the
> > one
> > touched in this patch: intel_crtc_disable_noatomic(). In your previous
> > series
> > you dropped that call based on the fact that there shouldn't be any pending
> > flips at that point, but that patch has been dropped.
> > 
> > Wouldn't it be better to add a WARN_ON as Chris suggested then instead of
> > keeping the wait for flips but without the work around?
> > 
> Apply with --scissors
> 
> ---8<------
> intel_crtc_disable_noatomic is called from hw readout during init, resume and
> possibly reset.
> During init it's too early to have a page flip queued, before suspending all
> page flips
> should be finished and during hw reset all page flips should be removed.
> 
> It's a bug when there are pending flips here, complain with WARN_ON instead of
> handling it.
> 
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> --
> diff --git a/drivers/gpu/drm/i915/intel_display.c
> b/drivers/gpu/drm/i915/intel_display.c
> index f59029c3e577..95c59b5202c5 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -6225,7 +6225,8 @@ static void intel_crtc_disable_noatomic(struct drm_crtc
> *crtc)
>  		return;
>  
>  	if (to_intel_plane_state(crtc->primary->state)->visible) {
> -		intel_crtc_wait_for_pending_flips(crtc);
> +		WARN_ON(intel_crtc->unpin_work);
> +
>  		intel_pre_disable_primary(crtc);
>  	}
>  
> 

Reviewed-by: Ander Conselvan de Oliveira <conselvan2@gmail.com>
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