[Intel-gfx] [PATCH 01/16] drm/i915: make sure we're not changing the FBC CFB with FBC enabled

[Ville Syrjälä]

On Fri, Aug 14, 2015 at 06:34:06PM -0300, Paulo Zanoni wrote:
> We used to have this bug in the past, but now that we properly track
> the size of the CFB, we don't have it anymore. Still, add the WARN
> just to make sure we don't go back to the bad state.
> 
> Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_fbc.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
> index 1f97fb5..c97aba2 100644
> --- a/drivers/gpu/drm/i915/intel_fbc.c
> +++ b/drivers/gpu/drm/i915/intel_fbc.c
> @@ -589,6 +589,8 @@ static int intel_fbc_alloc_cfb(struct drm_i915_private *dev_priv, int size,
>  
>  	dev_priv->fbc.threshold = ret;
>  
> +	WARN_ON(dev_priv->fbc.enabled);
> +

We should really check it already before we free the stolen memory (or
maybe sprinkle it to both places?), and we should make sure FBC really
got disabled, ie. at last one vblank must have occured since the enable
bit was cleared.

Since we lack the vblank workers, I think having this WARN before the
stolen is freed, with a FIXME about the disable vs. vblank issue would
be acceptable.

>  	if (INTEL_INFO(dev_priv)->gen >= 5)
>  		I915_WRITE(ILK_DPFC_CB_BASE, dev_priv->fbc.compressed_fb.start);
>  	else if (IS_GM45(dev_priv)) {
> -- 
> 2.4.6
> 
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-- 
Ville Syrjälä
Intel OTC