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

[Ben Widawsky <ben@bwidawsk.net>]

On Fri, Jul 05, 2013 at 09:12:05AM +0200, Daniel Vetter wrote:
> On Thu, Jul 04, 2013 at 11:24:46PM +0200, Daniel Vetter wrote:
> > 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);
> > 
> > I've thought we've agreed on a WARN_ON(!drm_mm_node_allocated); here?
> 
> WARN_ON(drm_mm_node_allocated); to be precise ;-)
> -Daniel

To be honest, I forgot - but the original plan was to do it after the
node embedding. I think for the same paranoia, we also want to check
that obj->gtt_space != NULL.

Would you mind adding it on merge?

-- 
Ben Widawsky, Intel Open Source Technology Center