Re: [PATCH v2 for -fixes] drm/i915: Disable stolen memory when DMAR is active

[Daniel Vetter <daniel@ffwll.ch>]

On Tue, Mar 18, 2014 at 02:59:04PM +0200, Jani Nikula wrote:
> From: Chris Wilson <chris@chris-wilson.co.uk>
> 
> We have reports of heavy screen corruption if we try to use the stolen
> memory reserved by the BIOS whilst the DMA-Remapper is active. This
> quirk may be only specific to a few machines or BIOSes, but first lets
> apply the big hammer and always disable use of stolen memory when DMAR
> is active.
> 
> v2 by Jani: Rebase on -fixes, only look at intel_iommu_gfx_mapped.
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=68535
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> 
> ---
> 
> Daniel, is this the color you want?

Yeah, colour looks shiny ;-) Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> 
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_gem_stolen.c |    7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c
> index d58b4e287e32..28d24caa49f3 100644
> --- a/drivers/gpu/drm/i915/i915_gem_stolen.c
> +++ b/drivers/gpu/drm/i915/i915_gem_stolen.c
> @@ -214,6 +214,13 @@ int i915_gem_init_stolen(struct drm_device *dev)
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  	int bios_reserved = 0;
>  
> +#ifdef CONFIG_INTEL_IOMMU
> +	if (intel_iommu_gfx_mapped) {
> +		DRM_INFO("DMAR active, disabling use of stolen memory\n");
> +		return 0;
> +	}
> +#endif
> +
>  	if (dev_priv->gtt.stolen_size == 0)
>  		return 0;
>  
> -- 
> 1.7.9.5
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch