Re: [PATCH 07/13] drm/i915: don't disable_fbc() if FBC is already disabled

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Nov 04, 2015 at 05:10:51PM -0200, Paulo Zanoni wrote:
> If FBC is disabled we will still call intel_fbc_invalidate(), and as a
> result we may call intel_fbc_deactivate(), which will try to touch
> registers.
> 
> I'm pretty sure I saw this happen on a runtime suspended device, and

This is one of the BAT failures we have. I don't really understand why
we track the frontbuffer bits with FBC totally disabled, but this fix
seems simple enough on its own. Not sure if it applies without the
others, but if it doesn't I suggest trying to reorder the patchset so
we can put this in ASAP.

> I'm almost sure I was running igt/pm_rpm. It produced the "you touched
> registers while the device is suspended" WARNs. But this was some time
> ago and I can't remember exactly which conditions were necessary to
> reproduce the problem.
> 
> v2: Rebase to new series order.
> 
> Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_fbc.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
> index dfb8657..5a853c6 100644
> --- a/drivers/gpu/drm/i915/intel_fbc.c
> +++ b/drivers/gpu/drm/i915/intel_fbc.c
> @@ -438,7 +438,8 @@ static void __intel_fbc_disable(struct drm_i915_private *dev_priv)
>  
>  	intel_fbc_cancel_work(dev_priv);
>  
> -	dev_priv->fbc.disable_fbc(dev_priv);
> +	if (dev_priv->fbc.enabled)
> +		dev_priv->fbc.disable_fbc(dev_priv);
>  	dev_priv->fbc.crtc = NULL;
>  }
>  
> -- 
> 2.6.1
> 
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-- 
Ville Syrjälä
Intel OTC
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