Re: [PATCH] drm/i915: add energy counter support for IVB

[Eugeni Dodonov <eugeni.dodonov@linux.intel.com>]

On 06/20/2012 12:59 PM, Daniel Vetter wrote:
> On Wed, Jun 20, 2012 at 5:53 PM, Chris Wilson <chris@chris-wilson.co.uk> wrote:
>> On Wed, 20 Jun 2012 08:32:59 -0700, Jesse Barnes <jbarnes@virtuousgeek.org> wrote:
>>> On Wed, 20 Jun 2012 09:38:25 +0200
>>> Daniel Vetter <daniel@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+.
> 
> At that point you might also add the uJ suffix and move it to sysfs ;-)

And as a final minor suggestion, could we integrate this with the
/sys/kernel/debug/dri/0/i915_emon_status we have on ILK, so we could
have just one file for power readings?

Eugeni