Re: [PATCH v4] drm/i915: rc6 in sysfs

[Daniel Vetter <daniel@ffwll.ch>]

On Wed, Apr 11, 2012 at 09:14:43AM +0100, Chris Wilson wrote:
> On Tue, 10 Apr 2012 21:17:01 -0700, Ben Widawsky <ben@bwidawsk.net> wrote:
> > Merge rc6 information into the power group for our device. Until now the
> > i915 driver has not had any sysfs entries (aside from the connector
> > stuff enabled by drm core). Since it seems like we're likely to have
> > more in the future I created a new file for sysfs stubs, as well as the
> > rc6 sysfs functions which don't really belong elsewhere (perhaps
> > i915_suspend, but most of the stuff is in intel_display,c).
> > 
> > displays rc6 modes enabled (as a hex mask):
> > cat /sys/class/drm/card0/power/rc6_enable
> > 
> > displays #ms GPU has been in rc6 since boot:
> > cat /sys/class/drm/card0/power/rc6_residency_ms
> > 
> > displays #ms GPU has been in deep rc6 since boot:
> > cat /sys/class/drm/card0/power/rc6p_residency_ms
> > 
> > displays #ms GPU has been in deepest rc6 since boot:
> > cat /sys/class/drm/card0/power/rc6pp_residency_ms
> > 
> > Important note: I've seen on SNB that even when RC6 is *not* enabled the
> > rc6 register seems to have a random value in it. I can only guess at the
> > reason reason for this. Those writing tools that utilize this value need
> > to be careful and probably want to scrutinize the value very carefully.
> > 
> > v2: use common rc6 residency units to milliseconds for the other RC6 types
> > 
> > v3: don't create sysfs files for GEN <= 5
> > add a rc6_enable to show a mask of enabled rc6 types
> > use unmerge instead of remove for sysfs group
> > squash intel_enable_rc6() extraction into this patch
> > 
> > v4: rename sysfs files (Chris)
> > 
> > CC: Chris Wilson <chris@chris-wilson.co.uk>
> > CC: Daniel Vetter <daniel.vetter@ffwll.ch>f
> > CC: Arjan van de Ven <arjan@linux.intel.com>
> > Signed-off-by: Ben Widawsky <benjamin.widawsky@intel.com>
> 
> So the only downside to using the pre-existing power group is that we do
> not get the interface if power-management is compiled out of the kernel,
> which I suppose is appropriate.
> 
> I'm down to just bikeshedding over useless lines of code which do not
> even add visual clarity...
> 
> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Queued for -next, thanks for the patch.
-Daniel
-- 
Daniel Vetter
Mail: daniel@ffwll.ch
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