Re: [PATCH 1/2] drm/i915: fix DDI PLLs HW state readout code

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Jan 08, 2014 at 03:53:28PM +0100, Daniel Vetter wrote:
> On Wed, Jan 08, 2014 at 11:12:27AM -0200, Paulo Zanoni wrote:
> > From: Paulo Zanoni <paulo.r.zanoni@intel.com>
> > 
> > Properly zero the refcounts and crtc->ddi_pll_set so the previous HW
> > state doesn't affect the result of reading the current HW state.
> > 
> > This fixes WARNs about WRPLL refcount if we have an HDMI monitor on
> > HSW and then suspend/resume.
> > 
> > Cc: stable@vger.kernel.org
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=64379
> > Tested-by: Qingshuai Tian <qingshuai.tian@intel.com>
> > Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_ddi.c | 8 +++++++-
> >  1 file changed, 7 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> > index 4ec1665..0def5ef 100644
> > --- a/drivers/gpu/drm/i915/intel_ddi.c
> > +++ b/drivers/gpu/drm/i915/intel_ddi.c
> > @@ -1136,12 +1136,18 @@ void intel_ddi_setup_hw_pll_state(struct drm_device *dev)
> >  	enum pipe pipe;
> >  	struct intel_crtc *intel_crtc;
> >  
> > +	dev_priv->ddi_plls.spll_refcount = 0;
> > +	dev_priv->ddi_plls.wrpll1_refcount = 0;
> > +	dev_priv->ddi_plls.wrpll2_refcount = 0;
> 
> One idea I have for the longer-term is to unify the ddi pll
> refcounting/readout stuff with the logic I've created for shared pch plls.
> The pch pll sharing checks and refcount logic is now really solid and
> completely paranoid with self-checks, and it took about 10 iterations to
> get there in a mostly bug-free manner. It looks a bit like ddi pll sharing
> is on track to duplicate that, so merging them would be benificial. It
> might also help the state pre-computation stuff we still need to do for
> plls.

We might also want to look into PLL sharing on VLV as well.

-- 
Ville Syrjälä
Intel OTC