Re: [PATCH] drm/i915: Don't use a special stolen reserve offset

From: Daniel Vetter <daniel@ffwll.ch>
To: Ben Widawsky <ben@bwidawsk.net>
Cc: Intel GFX <intel-gfx@lists.freedesktop.org>
Subject: Re: [PATCH] drm/i915: Don't use a special stolen reserve offset
Date: Fri, 5 Jul 2013 21:22:03 +0200	[thread overview]
Message-ID: <20130705192203.GV18285@phenom.ffwll.local> (raw)
In-Reply-To: <1372966935-18966-1-git-send-email-ben@bwidawsk.net>

On Thu, Jul 04, 2013 at 12:42:15PM -0700, Ben Widawsky wrote:
> Setting the node directly is good enough. We don't need a special value
> to store the gtt_offset, and we no longer have the pointer to tuck
> things away neatly.
> 
> This is temporarily broken since:
> commit 7dedae28b41000539b6c18bcf72107c97e4937e4
> Author: Ben Widawsky <ben@bwidawsk.net>
> Date:   Wed Jul 3 14:45:24 2013 -0700
> 
>     drm/i915: Use gtt_space->start for stolen reservation
> 
> However with no userspace currently, the bisection problem shouldn't be
> a concern.
> 
> CC: Chris Wilson <chris@chris-wilson.co.uk>
> Reported-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
> ---
>  drivers/gpu/drm/i915/i915_drv.h        | 1 -
>  drivers/gpu/drm/i915/i915_gem_gtt.c    | 1 -
>  drivers/gpu/drm/i915/i915_gem_stolen.c | 8 ++++++--
>  3 files changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index ea86ad6..b9e8ba1 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1201,7 +1201,6 @@ enum hdmi_force_audio {
>  	HDMI_AUDIO_ON,			/* force turn on HDMI audio */
>  };
>  
> -#define I915_GTT_RESERVED (ULONG_MAX)
>  #define I915_GTT_OFFSET_NONE ((u32)-1)
>  
>  struct drm_i915_gem_object_ops {
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index f075831..c0ca103 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -632,7 +632,6 @@ 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->gtt_space->start != I915_GTT_RESERVED);
>  		obj->gtt_space = drm_mm_create_block(&dev_priv->mm.gtt_space,
>  						     i915_gem_obj_ggtt_offset(obj),
>  						     obj->base.size,
> diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c
> index c6b70312..289d511d 100644
> --- a/drivers/gpu/drm/i915/i915_gem_stolen.c
> +++ b/drivers/gpu/drm/i915/i915_gem_stolen.c
> @@ -397,8 +397,12 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
>  			drm_gem_object_unreference(&obj->base);
>  			return NULL;
>  		}
> -	} else
> -		obj->gtt_space->start = I915_GTT_RESERVED;
> +	} else {
> +		/* Generally it isn't safe to directly set attributes of the
> +		 * drm_mm_node, however this is a special case where we'll
> +		 * promise to handle everything properly later. */
> +		obj->gtt_space->start = gtt_offset;

Since obj->gtt_space isn't embedded yet this will blow up. I think we need
to do the embedding first, then fix this up.
-Daniel

> +	}
>  
>  	obj->has_global_gtt_mapping = 1;
>  
> -- 
> 1.8.3.2
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

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