[Intel-gfx] [PATCH] drm/i915: add turbo boost trace point

[Chris Wilson]

On Wed, Nov 19, 2014 at 03:00:04PM +0100, Daniel Vetter wrote:
> On Tue, Nov 18, 2014 at 01:12:29PM -0800, Jesse Barnes wrote:
> > Might be helpful for debugging places where userspace ends up boosting
> > or waiting where it doesn't intend to.
> 
> Might be feels a bit weak justification for a new tracepoint imo. Please
> drum up more support.
> 
> > Signed-off-by: Jesse Barnes <jbarnes at virtuousgeek.org>
> > ---
> >  drivers/gpu/drm/i915/i915_gem.c   |  6 ++++--
> >  drivers/gpu/drm/i915/i915_trace.h | 15 +++++++++++++++
> >  drivers/gpu/drm/i915/intel_pm.c   |  9 +++++++--
> >  3 files changed, 26 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> > index 86cf428..b03cb07 100644
> > --- a/drivers/gpu/drm/i915/i915_gem.c
> > +++ b/drivers/gpu/drm/i915/i915_gem.c
> > @@ -4209,8 +4209,10 @@ i915_gem_object_ggtt_unpin(struct drm_i915_gem_object *obj)
> >  	struct i915_vma *vma = i915_gem_obj_to_ggtt(obj);
> >  
> >  	BUG_ON(!vma);
> > -	BUG_ON(vma->pin_count == 0);
> > -	BUG_ON(!i915_gem_obj_ggtt_bound(obj));
> > +	if (WARN(vma->pin_count == 0, "bad pin count\n"))
> > +		return;
> > +	if (WARN(!i915_gem_obj_ggtt_bound(obj), "obj not bound\n"))
> > +		return;
> 
> Separate patch. Can you please split it out with the usual "BUG_ON
> considered harmful" commit message?

I have argued that these represent extreme fail on the part of the
programmer - you have left the hardware accessing random physical pages
in the system, game over.

I need a stronger argument than that because presumably Jesse did end up
fixing whatever he did actually blow up.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre