[Intel-gfx] [PATCH 7/9] drm/i915: allow package C8+ states on Haswell (disabled)

[Daniel Vetter]

On Wed, Aug 07, 2013 at 03:20:09PM +0100, Chris Wilson wrote:
> On Wed, Aug 07, 2013 at 10:38:19AM -0300, Paulo Zanoni wrote:
> > 2013/8/6 Chris Wilson <chris at chris-wilson.co.uk>:
> > > On Tue, Aug 06, 2013 at 06:57:17PM -0300, Paulo Zanoni wrote:
> > >> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
> > >> index 2ef4335..7f6ec9e 100644
> > >> --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
> > >> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
> > >> @@ -1590,6 +1590,8 @@ void intel_ring_advance(struct intel_ring_buffer *ring)
> > >>  {
> > >>       struct drm_i915_private *dev_priv = ring->dev->dev_private;
> > >>
> > >> +     hsw_package_c8_gpu_busy(dev_priv);
> > >> +
> > >
> > > Ahem, what is this doing here? If only we had something that was the
> > > opposite of intel_mark_idle... At this point, I am going to get some
> > > sleep...
> > 
> > You're suggesting me to use intel_mark_busy? I have to admit I saw it,
> > but I noticed intel_mark_busy is called after intel_ring_advance, and
> > I was trying to follow what Ben suggested me. If you're suggesting
> > this, I guess it's ok, so I will test this possibility.
> 
> intel_mark_busy() is where we note the transition in userspace activity,
> it should be where we put all the little hooks and pm tweaks required.
> If you however need the pc8 disable earlier than the ring register write,
> we should do it in intel_ring_begin(). Ultimately, though we should be
> able to squash it into a single operation such that we never submit a
> command before intel_mark_busy(). Hmm, easier in fact just to move
> intel_mark_busy() to intel_ring_begin() and I think everybody is happy.

We have oddball places where we add stuff to the ring but not a request,
so we'd miss the eventual mark_idle. But since this is only to make sure
we have working interrupts the current place of mark_busy should be good
enough.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch