[Intel-gfx] [PATCH 02/16] drm/i915: fix the FBC work allocation failure path

[Ville Syrjälä]

On Fri, Aug 14, 2015 at 06:34:07PM -0300, Paulo Zanoni wrote:
> Always update the currrent crtc, fb and vertical offset after calling
> enable_fbc. We were forgetting to do so along the failure paths when
> enabling fbc synchronously. Fix this with a new helper to enable_fbc()
> and update the state simultaneously.
> 
> v2: Improve commit message (Chris).
> 
> Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_fbc.c | 27 +++++++++++++++++----------
>  1 file changed, 17 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
> index c97aba2..fa9b004 100644
> --- a/drivers/gpu/drm/i915/intel_fbc.c
> +++ b/drivers/gpu/drm/i915/intel_fbc.c
> @@ -308,6 +308,18 @@ bool intel_fbc_enabled(struct drm_i915_private *dev_priv)
>  	return dev_priv->fbc.enabled;
>  }
>  
> +static void intel_fbc_enable(struct intel_crtc *crtc,
> +			     struct drm_framebuffer *fb)

fb could be const

> +{
> +	struct drm_i915_private *dev_priv = crtc->base.dev->dev_private;
> +
> +	dev_priv->fbc.enable_fbc(crtc);
> +
> +	dev_priv->fbc.crtc = crtc;
> +	dev_priv->fbc.fb_id = fb->base.id;
> +	dev_priv->fbc.y = crtc->base.y;
> +}
> +
>  static void intel_fbc_work_fn(struct work_struct *__work)
>  {
>  	struct intel_fbc_work *work =
> @@ -321,13 +333,8 @@ static void intel_fbc_work_fn(struct work_struct *__work)
>  		/* Double check that we haven't switched fb without cancelling
>  		 * the prior work.
>  		 */
> -		if (crtc_fb == work->fb) {
> -			dev_priv->fbc.enable_fbc(work->crtc);
> -
> -			dev_priv->fbc.crtc = work->crtc;
> -			dev_priv->fbc.fb_id = crtc_fb->base.id;
> -			dev_priv->fbc.y = work->crtc->base.y;
> -		}
> +		if (crtc_fb == work->fb)
> +			intel_fbc_enable(work->crtc, work->fb);

The no locking or refcounts nature of this scares me, and should be
dealt with eventually.

But in the meantime it makes things nicer, so
Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

>  
>  		dev_priv->fbc.fbc_work = NULL;
>  	}
> @@ -361,7 +368,7 @@ static void intel_fbc_cancel_work(struct drm_i915_private *dev_priv)
>  	dev_priv->fbc.fbc_work = NULL;
>  }
>  
> -static void intel_fbc_enable(struct intel_crtc *crtc)
> +static void intel_fbc_schedule_enable(struct intel_crtc *crtc)
>  {
>  	struct intel_fbc_work *work;
>  	struct drm_i915_private *dev_priv = crtc->base.dev->dev_private;
> @@ -373,7 +380,7 @@ static void intel_fbc_enable(struct intel_crtc *crtc)
>  	work = kzalloc(sizeof(*work), GFP_KERNEL);
>  	if (work == NULL) {
>  		DRM_ERROR("Failed to allocate FBC work structure\n");
> -		dev_priv->fbc.enable_fbc(crtc);
> +		intel_fbc_enable(crtc, crtc->base.primary->fb);
>  		return;
>  	}

BTW getting rid of this allocation would be nice. Would be one less
thing that can fail...

>  
> @@ -826,7 +833,7 @@ static void __intel_fbc_update(struct drm_i915_private *dev_priv)
>  		__intel_fbc_disable(dev_priv);
>  	}
>  
> -	intel_fbc_enable(intel_crtc);
> +	intel_fbc_schedule_enable(intel_crtc);
>  	dev_priv->fbc.no_fbc_reason = FBC_OK;
>  	return;
>  
> -- 
> 2.4.6
> 
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-- 
Ville Syrjälä
Intel OTC