[PATCH 6/6] drm/i915: Sanitize drm crtc vblank counter after DC reset frame count.

[Daniel Vetter]

On Wed, Aug 03, 2016 at 02:33:39PM -0700, Rodrigo Vivi wrote:
> DC state reset the frame counter that is a read-only register.
> 
> So, besides blocking DC state on vblank let's restore the
> drm crtc vblank counter to a place we know it is reliable.
> 
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_irq.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 4efe20c..82d6896 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -2759,7 +2759,9 @@ static int gen8_enable_vblank(struct drm_device *dev, unsigned int pipe)
>  static void gen9_prepare_vblank(struct drm_device *dev, unsigned int pipe)
>  {
>  	struct drm_i915_private *dev_priv = to_i915(dev);
> +	struct drm_crtc *crtc = dev_priv->pipe_to_crtc_mapping[pipe];
>  	intel_display_power_get(dev_priv, POWER_DOMAIN_VBLANK);
> +	drm_crtc_vblank_sanitize_counter(crtc);

I think this should be done within the platform power code. Otherwise
something else might keep the system out of dc states, but then we might
wreak havoc by calling this function here.
-Daniel

>  }
>  
>  static void gen9_unprepare_vblank(struct drm_device *dev, unsigned int pipe)
> -- 
> 2.4.3
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch