[Intel-gfx] [PATCH] drm/i915: Avoid reading fbc registers in vain when fbc was never enabled.

[Chris Wilson]

On Wed, Sep 17, 2014 at 04:59:20PM -0400, Rodrigo Vivi wrote:
> If it wasn't never enabled by kernel parameter or platform default
> we can avoid reading registers so many times in vain

Nak.
 
> Cc: Paulo Zanoni <paulo.r.zanoni at intel.com>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_pm.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index a988862..afcc284 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -339,6 +339,12 @@ bool intel_fbc_enabled(struct drm_device *dev)
>  {
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  
> +	/* If it wasn't never enabled by kernel parameter or platform default
> +	 * we can avoid reading registers so many times in vain
> +	 */
> +	if (!i915.enable_fbc)
> +		return false;
> +
>  	if (!dev_priv->display.fbc_enabled)
>  		return false;

The correct state to check here is whether we have enabled fbc, not the
module parameter which just rules whether we should turn it on.
Look at making dev_priv->fbc.no_fbc_reason always correct instead.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre