[Intel-gfx] [PATCH 05/32] drm/i915: Simplify checking of GPU reset_counter in display pageflips

[Daniel Vetter]

On Fri, Dec 11, 2015 at 11:33:01AM +0000, Chris Wilson wrote:
> If we, when we store the reset_counter for the operation, we ensure that
> it is not in a wedged or in the middle of a reset, we can then assert that
> if any reset occurs the reset_counter must change. Later we can just
> compare the operation's reset epoch against the current counter to see
> if we need to abort the operation (to handle the hang).
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>

Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>

> ---
>  drivers/gpu/drm/i915/intel_display.c | 16 +++++++++-------
>  1 file changed, 9 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index cc47c0206294..8b6028cd619f 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -3283,14 +3283,12 @@ void intel_finish_reset(struct drm_device *dev)
>  static bool intel_crtc_has_pending_flip(struct drm_crtc *crtc)
>  {
>  	struct drm_device *dev = crtc->dev;
> -	struct drm_i915_private *dev_priv = dev->dev_private;
>  	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
>  	unsigned reset_counter;
>  	bool pending;
>  
> -	reset_counter = i915_reset_counter(&dev_priv->gpu_error);
> -	if (intel_crtc->reset_counter != reset_counter ||
> -	    __i915_reset_in_progress_or_wedged(reset_counter))
> +	reset_counter = i915_reset_counter(&to_i915(dev)->gpu_error);
> +	if (intel_crtc->reset_counter != reset_counter)
>  		return false;
>  
>  	spin_lock_irq(&dev->event_lock);
> @@ -10947,8 +10945,7 @@ static bool page_flip_finished(struct intel_crtc *crtc)
>  	unsigned reset_counter;
>  
>  	reset_counter = i915_reset_counter(&dev_priv->gpu_error);
> -	if (crtc->reset_counter != reset_counter ||
> -	    __i915_reset_in_progress_or_wedged(reset_counter))
> +	if (crtc->reset_counter != reset_counter)
>  		return true;
>  
>  	/*
> @@ -11604,8 +11601,13 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
>  	if (ret)
>  		goto cleanup;
>  
> -	atomic_inc(&intel_crtc->unpin_work_count);
>  	intel_crtc->reset_counter = i915_reset_counter(&dev_priv->gpu_error);
> +	if (__i915_reset_in_progress_or_wedged(intel_crtc->reset_counter)) {
> +		ret = -EIO;
> +		goto cleanup;
> +	}
> +
> +	atomic_inc(&intel_crtc->unpin_work_count);
>  
>  	if (INTEL_INFO(dev)->gen >= 5 || IS_G4X(dev))
>  		work->flip_count = I915_READ(PIPE_FLIPCOUNT_G4X(pipe)) + 1;
> -- 
> 2.6.3
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch