Re: [PATCH v3 01/11] drm/i915: Store max dotclock

[Mika Kahola <mika.kahola@intel.com>]

On Wed, 2015-08-12 at 22:01 +0300, Ville Syrjälä wrote:
> On Wed, Aug 12, 2015 at 08:30:23PM +0300, Ville Syrjälä wrote:
> > On Fri, Jul 31, 2015 at 03:13:50PM +0300, Mika Kahola wrote:
> > > Store max dotclock into dev_priv structure so we are able
> > > to filter out the modes that are not supported by our
> > > platforms.
> > > 
> > > V2:
> > > - limit the max dot clock frequency to max CD clock frequency
> > >   for the gen9 and above
> > > - limit the max dot clock frequency to 90% of the max CD clock
> > >   frequency for the older gens
> > > - for Cherryview the max dot clock frequency is limited to 95%
> > >   of the max CD clock frequency
> > > - for gen2 and gen3 the max dot clock limit is set to 90% of the
> > >   2X max CD clock frequency
> > > 
> > > Signed-off-by: Mika Kahola <mika.kahola@intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/i915_drv.h      |  1 +
> > >  drivers/gpu/drm/i915/intel_display.c | 19 +++++++++++++++++++
> > >  2 files changed, 20 insertions(+)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> > > index 04aa34a..1f69211b 100644
> > > --- a/drivers/gpu/drm/i915/i915_drv.h
> > > +++ b/drivers/gpu/drm/i915/i915_drv.h
> > > @@ -1777,6 +1777,7 @@ struct drm_i915_private {
> > >  	unsigned int fsb_freq, mem_freq, is_ddr3;
> > >  	unsigned int skl_boot_cdclk;
> > >  	unsigned int cdclk_freq, max_cdclk_freq;
> > > +	unsigned int max_dotclk;
> > 
> > nit: maybe max_dotclk_freq for extra consistentcy?
> > 
> > >  	unsigned int hpll_freq;
> > >  
> > >  	/**
> > > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > > index 43b0f17..c9c6d19 100644
> > > --- a/drivers/gpu/drm/i915/intel_display.c
> > > +++ b/drivers/gpu/drm/i915/intel_display.c
> > > @@ -5259,6 +5259,23 @@ static void modeset_update_crtc_power_domains(struct drm_atomic_state *state)
> > >  			modeset_put_power_domains(dev_priv, put_domains[i]);
> > >  }
> > >  
> > > +static int intel_compute_max_dotclk(struct drm_i915_private *dev_priv)
> > > +{
> > > +	int max_cdclk_freq = dev_priv->max_cdclk_freq;
> > > +	int max_dotclk_freq;
> > > +
> > > +	if (INTEL_INFO(dev_priv)->gen >= 9)
> > > +		max_dotclk_freq = max_cdclk_freq;
> > > +	else if (IS_CHERRYVIEW(dev_priv))
> > > +		max_dotclk_freq = DIV_ROUND_UP(max_cdclk_freq * 95, 100);
> > > +	else if (INTEL_INFO(dev_priv)->gen == 2 || INTEL_INFO(dev_priv)->gen == 3)
> > 
> > intel_crtc_compute_config() uses 'gen < 4' as the condition around the
> > double_wide handling. Maybe do the same here for consistency.
> > 
> > > +		max_dotclk_freq = DIV_ROUND_UP(2 * max_cdclk_freq * 90, 100);
> > > +	else
> > > +		max_dotclk_freq = DIV_ROUND_UP(max_cdclk_freq * 90, 100);
> > 
> > These should round down to match what we do in the calc_cdclk funcs.
> > 
> > Also to add another bikeshed color, there's no need for the local
> > max_dotclk_freq variable, you can just 'return <whatever>' from each
> > branch.
> > 
> > With at least the rounding fixed this can have
> > Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > > +
> > > +	return max_dotclk_freq;
> > > +}
> > > +
> > >  static void intel_update_max_cdclk(struct drm_device *dev)
> > >  {
> > >  	struct drm_i915_private *dev_priv = dev->dev_private;
> > > @@ -5298,6 +5315,8 @@ static void intel_update_max_cdclk(struct drm_device *dev)
> > >  		dev_priv->max_cdclk_freq = dev_priv->cdclk_freq;
> > >  	}
> > >  
> > > +	dev_priv->max_dotclk = intel_compute_max_dotclk(dev_priv);
> > > +
> > >  	DRM_DEBUG_DRIVER("Max CD clock rate: %d kHz\n",
> > >  			 dev_priv->max_cdclk_freq);
> 
> Oh and I think it would be nice to add a DRM_DEBUG_DRIVER for the
> compute max_dotclk so that we'll have it handy in bug reports without
> having to recompute it in ones head.
> 
Thanks Ville for the review. I will work my way up towards v4 based on
your comments.

Cheers,
Mika

> > >  }
> > > -- 
> > > 1.9.1
> > > 
> > > _______________________________________________
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> > > Intel-gfx@lists.freedesktop.org
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> > 
> > -- 
> > Ville Syrjälä
> > Intel OTC
> 


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