Re: [PATCH] drm/mm: Don't WARN if drm_mm_reserve_node

[Ben Widawsky <benjamin.widawsky@intel.com>]

On Mon, Apr 07, 2014 at 10:13:13PM -0700, Jesse Barnes wrote:
> On Mon,  7 Apr 2014 23:25:20 +0200
> Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
> 
> > Jesse's BIOS fb reconstruction code actually relies on the -ENOSPC
> > return value to detect overlapping framebuffers (which the bios uses
> > always when lighting up more than one screen). All this fanciness
> > happens in intel_alloc_plane_obj in intel_display.c.
> > 
> > Since no one else uses this we can savely remove the WARN without
> > repercursions.
> > 
> > Reported-by: Ben Widawsky <benjamin.widawsky@intel.com>
> > Cc: Ben Widawsky <benjamin.widawsky@intel.com>
> > Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
> > Cc: Dave Airlie <airlied@redhat.com>
> > Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> > ---
> >  drivers/gpu/drm/drm_mm.c | 2 --
> >  1 file changed, 2 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
> > index a2d45b748f86..e4dfd5c3b15e 100644
> > --- a/drivers/gpu/drm/drm_mm.c
> > +++ b/drivers/gpu/drm/drm_mm.c
> > @@ -192,8 +192,6 @@ int drm_mm_reserve_node(struct drm_mm *mm, struct drm_mm_node *node)
> >  		return 0;
> >  	}
> >  
> > -	WARN(1, "no hole found for node 0x%lx + 0x%lx\n",
> > -	     node->start, node->size);
> >  	return -ENOSPC;
> >  }
> >  EXPORT_SYMBOL(drm_mm_reserve_node);
> 
> Yeah thanks, pushing this has been on my list for weeks now...

I am not convinced this is the correct solution. At least the way we
used this interface, it isn't meant to ever fail.  I also didn't look
into exactly why we depend an ENOSPC return. That sounds fragile to me,
especially for a public interface.

Obviously it makes the WARN go away, and we have only one other user of
the interface, so it's correct.

So if both of you are happy, I won't stand in the way.

-- 
Ben Widawsky, Intel Open Source Technology Center