Re: [PATCH] drm/i915/vlv: drop punit freq staus read after setting idle

[Jesse Barnes <jbarnes@virtuousgeek.org>]

On Fri, 6 Jun 2014 11:29:24 +0300
Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:

> On Thu, Jun 05, 2014 at 01:49:34PM -0700, Jesse Barnes wrote:
> > This may take awhile (~10ms), and we don't need to make noise about it.
> > 
> > References: https://bugs.freedesktop.org/show_bug.cgi?id=75244
> > Tested-by: huax.lu@intel.com
> > Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
> > ---
> >  drivers/gpu/drm/i915/intel_pm.c | 4 ----
> >  1 file changed, 4 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> > index ee27d74..4eebfd8 100644
> > --- a/drivers/gpu/drm/i915/intel_pm.c
> > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > @@ -3227,10 +3227,6 @@ static void vlv_set_rps_idle(struct drm_i915_private *dev_priv)
> >  	vlv_punit_write(dev_priv, PUNIT_REG_GPU_FREQ_REQ,
> >  					dev_priv->rps.min_freq_softlimit);
> >  
> > -	if (wait_for(((vlv_punit_read(dev_priv, PUNIT_REG_GPU_FREQ_STS))
> > -				& GENFREQSTATUS) == 0, 5))
> > -		DRM_ERROR("timed out waiting for Punit\n");
> > -
> 
> As I recall the entire point of this was to make sure the frequency
> really drops before we allow turning off the clock. I'm not sure if we
> can trust that the frequency (and more importantly the voltage) will
> drop if we allow turning off the clock before the transition is
> complete.

well, we may need to increase the timeout then... let's see if that
helps with the bug.

-- 
Jesse Barnes, Intel Open Source Technology Center
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