[Intel-gfx] [PATCH 4/6] drm/i915: Use gtt_space->start for stolen reservation

[Daniel Vetter]

On Wed, Jul 03, 2013 at 02:45:24PM -0700, Ben Widawsky wrote:
> Shortly we'll want to switch to an embedded drm_mm_node per object, and
> therefore using pointers as we're doing is unfeasible.
> 
> I've chosen an impossible gtt start offset as the way to denote a
> reservation.
> 
> CC: Chris Wilson <chris at chris-wilson.co.uk>
> Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
> ---
>  drivers/gpu/drm/i915/i915_drv.h        | 2 +-
>  drivers/gpu/drm/i915/i915_gem_gtt.c    | 2 +-
>  drivers/gpu/drm/i915/i915_gem_stolen.c | 2 +-
>  3 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index d06886b..b6864ffb 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1201,7 +1201,7 @@ enum hdmi_force_audio {
>  	HDMI_AUDIO_ON,			/* force turn on HDMI audio */
>  };
>  
> -#define I915_GTT_RESERVED ((struct drm_mm_node *)0x1)
> +#define I915_GTT_RESERVED (dev_priv->gtt.total + 1)

This is _really_ fragile since if we every change gtt.total in the init
sequence this will blow up. I've switched over to an appropriate real
constant (ULONG_MAX).
-Daniel


>  
>  struct drm_i915_gem_object_ops {
>  	/* Interface between the GEM object and its backing storage.
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index 1eefba7..fbe2e72 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -633,7 +633,7 @@ void i915_gem_setup_global_gtt(struct drm_device *dev,
>  		DRM_DEBUG_KMS("reserving preallocated space: %lx + %zx\n",
>  			      i915_gem_obj_ggtt_offset(obj), obj->base.size);
>  
> -		BUG_ON(obj->ggtt_space != I915_GTT_RESERVED);
> +		BUG_ON(obj->ggtt_space->start != I915_GTT_RESERVED);
>  		obj->ggtt_space = kzalloc(sizeof(*obj->ggtt_space), GFP_KERNEL);
>  		if (!obj->ggtt_space) {
>  			DRM_ERROR("Failed to preserve all objects\n");
> diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c
> index 2f009e6..c9d7016 100644
> --- a/drivers/gpu/drm/i915/i915_gem_stolen.c
> +++ b/drivers/gpu/drm/i915/i915_gem_stolen.c
> @@ -388,7 +388,7 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
>  			goto unref_out;
>  		}
>  	} else
> -		obj->ggtt_space = I915_GTT_RESERVED;
> +		obj->ggtt_space->start = I915_GTT_RESERVED;
>  
>  	obj->has_global_gtt_mapping = 1;
>  
> -- 
> 1.8.3.2
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch