Re: [PATCH 2/3] drm/i915: Decouple the stuck pageflip on modeset

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Fri, May 30, 2014 at 05:16:35PM +0100, Chris Wilson wrote:
> If we successfully confuse the hardware, and cause it to drop a queued
> pageflip, we wait for 60s and issue a warning before continuing on with
> the modeset. However, this leaves the pending pageflip still stuck
> indefinitely. Pretend to userspace that it does complete, and let us
> start afresh following the modeset.
> 
> 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 | 18 +++++++++++++++---
>  1 file changed, 15 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 764b277e5937..54b69838e2de 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -3329,9 +3329,21 @@ void intel_crtc_wait_for_pending_flips(struct drm_crtc *crtc)
>  
>  	WARN_ON(waitqueue_active(&dev_priv->pending_flip_queue));
>  
> -	WARN_ON(wait_event_timeout(dev_priv->pending_flip_queue,
> -				   !intel_crtc_has_pending_flip(crtc),
> -				   60*HZ) == 0);
> +	if (WARN_ON(wait_event_timeout(dev_priv->pending_flip_queue,
> +				       !intel_crtc_has_pending_flip(crtc),
> +				       60*HZ) == 0)) {
> +		struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
> +		unsigned long flags;
> +
> +		spin_lock_irqsave(&dev->event_lock, flags);
> +		if (intel_crtc->unpin_work) {
> +			WARN_ONCE(1, "Removing stuck page flip\n");
> +			drm_vblank_put(dev, intel_crtc->pipe);
> +			page_flip_completed(dev_priv, intel_crtc, intel_crtc->unpin_work);
> +			intel_crtc->unpin_work = NULL;
> +		}
> +		spin_unlock_irqrestore(&dev->event_lock, flags);
> +	}

Seems like a decent idea.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Though my comment (to the other patch) about moving drm_vblank_put()
into page_flip_completed() still seems valid.

>  
>  	mutex_lock(&dev->struct_mutex);
>  	intel_finish_fb(crtc->primary->fb);
> -- 
> 2.0.0.rc4

-- 
Ville Syrjälä
Intel OTC