[Intel-gfx] [PATCH] drm/i915: add energy counter support for IVB

[Chris Wilson]

On Wed, 20 Jun 2012 08:32:59 -0700, Jesse Barnes <jbarnes at virtuousgeek.org> wrote:
> On Wed, 20 Jun 2012 09:38:25 +0200
> Daniel Vetter <daniel at ffwll.ch> wrote:
> > And from the bikeshed departement: Can't we just print a running number? I
> > know, substraction is bloody hard, but for anything else than total power
> > consumption (e.g. graphing power over time) the running thing is imo
> > simpler. We've had the same discussion for the rc6 sysfs residency timers
> > and concluded (after Arjan yelled at us) that doing the substraction in
> > userspace is better, least it allows multiple userspace tools to read
> > this.
> > 
> 
> Yeah that's a good point; this way happened to be simpler for what I
> was doing, but just exposing the cooked register value (converted to
> ujoules) is better.  Will fix.

And to keep it easy to parse, just make it return -ENODEV on older
platforms and a simple number for gen6+.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre