Re: [PATCH] drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake

From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: Chris Wilson <chris@chris-wilson.co.uk>
Cc: intel-gfx@lists.freedesktop.org, Paulo Zanoni <paulo.r.zanoni@intel.com>
Subject: Re: [PATCH] drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake
Date: Fri, 17 Jun 2016 22:34:38 +0300	[thread overview]
Message-ID: <20160617193438.GO4329@intel.com> (raw)
In-Reply-To: <1466181591-2984-1-git-send-email-chris@chris-wilson.co.uk>

On Fri, Jun 17, 2016 at 05:39:51PM +0100, Chris Wilson wrote:
> Erratum SKL075: Display Flicker May Occur When Both VT-d And FBC Are Enabled
> 
> "Display flickering may occur when both FBC (Frame Buffer Compression)
> and VT - d (Intel® Virtualization Technology for Directed I/O) are enabled
> and in use by the display controller."

WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl

> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_fbc.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
> index fddba1eed5ad..e47785467220 100644
> --- a/drivers/gpu/drm/i915/intel_fbc.c
> +++ b/drivers/gpu/drm/i915/intel_fbc.c
> @@ -1230,6 +1230,18 @@ void intel_fbc_init_pipe_state(struct drm_i915_private *dev_priv)
>  			dev_priv->fbc.visible_pipes_mask |= (1 << crtc->pipe);
>  }
>  
> +static bool need_vtd_wa(struct drm_i915_private *dev_priv)
> +{
> +#ifdef CONFIG_INTEL_IOMMU
> +	if (!intel_iommu_gfx_mapped)
> +		return false;
> +
> +	if (INTEL_GEN(dev_priv) == 9)
> +		return true;
> +#endif
> +	return false;
> +}
> +
>  /**
>   * intel_fbc_init - Initialize FBC
>   * @dev_priv: the i915 device
> @@ -1247,6 +1259,12 @@ void intel_fbc_init(struct drm_i915_private *dev_priv)
>  	fbc->active = false;
>  	fbc->work.scheduled = false;
>  
> +	if (need_vtd_wa(dev_priv)) {
> +		struct intel_device_info *info =
> +			(struct intel_device_info *)&dev_priv->info;
> +		info->has_fbc = false;
> +	}
> +
>  	if (!HAS_FBC(dev_priv)) {
>  		fbc->no_fbc_reason = "unsupported by this chipset";
>  		return;
> -- 
> 2.8.1
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Ville Syrjälä
Intel OTC
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx