Re: [PATCH 3/4] drm/i915: Store HPLL frequency in dev_priv on VLV

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

On Tue, Nov 05, 2013 at 01:02:58PM -0800, Jesse Barnes wrote:
> On Tue,  5 Nov 2013 22:42:30 +0200
> ville.syrjala@linux.intel.com wrote:
> 
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > Keep the HPLL frequencey in dev_priv on VLV instead of reading
> > it from CCK every time it's needed.
> > 
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_drv.h      | 2 +-
> >  drivers/gpu/drm/i915/intel_display.c | 7 ++++++-
> >  2 files changed, 7 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> > index 4bae871..dd40925 100644
> > --- a/drivers/gpu/drm/i915/i915_drv.h
> > +++ b/drivers/gpu/drm/i915/i915_drv.h
> > @@ -1360,7 +1360,7 @@ typedef struct drm_i915_private {
> >  	int fence_reg_start; /* 4 if userland hasn't ioctl'd us yet */
> >  	int num_fence_regs; /* 8 on pre-965, 16 otherwise */
> >  
> > -	unsigned int fsb_freq, mem_freq, is_ddr3;
> > +	unsigned int fsb_freq, mem_freq, is_ddr3, hpll_vco;
> >  
> >  	/**
> >  	 * wq - Driver workqueue for GEM.
> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > index 48f4990..f97e895 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -3898,13 +3898,18 @@ int valleyview_get_vco(struct drm_i915_private *dev_priv)
> >  {
> >  	int hpll_freq, vco_freq[] = { 800, 1600, 2000, 2400 };
> >  
> > +	if (dev_priv->hpll_vco)
> > +		return dev_priv->hpll_vco;
> > +
> >  	/* Obtain SKU information */
> >  	mutex_lock(&dev_priv->dpio_lock);
> >  	hpll_freq = vlv_cck_read(dev_priv, CCK_FUSE_REG) &
> >  		CCK_FUSE_HPLL_FREQ_MASK;
> >  	mutex_unlock(&dev_priv->dpio_lock);
> >  
> > -	return vco_freq[hpll_freq];
> > +	dev_priv->hpll_vco = vco_freq[hpll_freq];
> > +
> > +	return dev_priv->hpll_vco;
> >  }
> >  
> >  /* Adjust CDclk dividers to allow high res or save power if possible */
> 
> I'd just move this to init_clock_gating or something, then use
> dev_priv->hpll_vco everywhere, rather than this conditional lazy
> initialization.

The problem was the we need it at gmbus init time, and we do that very
early. So I couldn't figure out a nice place to stick it, and so
I ended up doing the lazy thing.

I suspect the best thing to do would be to move gmbus init to happen
later, alongside other modeset setup. But I'm feeling a bit lazy and
don't want to tackle that task right now.

Anyways, since we don't want patch 4/4, I think for now we can just
drop this one as well. The places where we call it currently aren't
really that frequent or performance sensitive.

-- 
Ville Syrjälä
Intel OTC