Re: [PATCH 28/67] drm/i915/cnl: Implement .get_display_clock_speed() for CNL

["Vivi, Rodrigo" <rodrigo.vivi@intel.com>]

On Fri, 2017-06-02 at 21:06 +0300, Imre Deak wrote:
> On Thu, Apr 06, 2017 at 12:15:24PM -0700, Rodrigo Vivi wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > Add support for reading out the cdclk frequency from the hardware on
> > CNL. Very similar to BXT, with a few new twists and turns:
> > * the PLL is now called CDCLK PLL, not DE PLL
> > * reference clock can be 24 MHz in addition to the 19.2 MHz BXT had
> > * the ratio now lives in the PLL enable register
> > * Only 1x and 2x CD2X dividers are supported
> > 
> > v2: Deal with PLL lock bit the same way as BXT/SKL do now
> > v3: DSSM refclk indicator is bit 31 not 24 (Ander)
> > v4: Rebased by Rodrigo after Ville's cdclk rework.
> > 
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_reg.h    |  5 ++++
> >  drivers/gpu/drm/i915/intel_cdclk.c | 54 +++++++++++++++++++++++++++++++++++++-
> >  2 files changed, 58 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> > index ac8a223..8353892 100644
> > --- a/drivers/gpu/drm/i915/i915_reg.h
> > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > @@ -6557,6 +6557,9 @@ enum {
> >  #define SKL_DFSM_PIPE_B_DISABLE		(1 << 21)
> >  #define SKL_DFSM_PIPE_C_DISABLE		(1 << 28)
> >  
> > +#define SKL_DSSM			_MMIO(0x51004)
> > +#define CNL_DSSM_CDCLK_PLL_REFCLK_24MHz	(1 << 31)
> > +
> >  #define GEN7_FF_SLICE_CS_CHICKEN1	_MMIO(0x20e0)
> >  #define   GEN9_FFSC_PERCTX_PREEMPT_CTRL	(1<<14)
> >  
> > @@ -8130,6 +8133,8 @@ enum {
> >  #define BXT_DE_PLL_ENABLE		_MMIO(0x46070)
> >  #define   BXT_DE_PLL_PLL_ENABLE		(1 << 31)
> >  #define   BXT_DE_PLL_LOCK		(1 << 30)
> > +#define   CNL_CDCLK_PLL_RATIO(x)	(x)	/* {28,44} * 19.2 or 24MHz */

> 
> Nit: 35,55 are also valid for 19.2MHz.

hm... should I just remove the comments then?!


> > +#define   CNL_CDCLK_PLL_RATIO_MASK	0xff
> >  
> >  /* GEN9 DC */
> >  #define DC_STATE_EN			_MMIO(0x45504)
> > diff --git a/drivers/gpu/drm/i915/intel_cdclk.c b/drivers/gpu/drm/i915/intel_cdclk.c
> > index 4745596..a4e2bd5 100644
> > --- a/drivers/gpu/drm/i915/intel_cdclk.c
> > +++ b/drivers/gpu/drm/i915/intel_cdclk.c
> > @@ -1400,6 +1400,56 @@ void bxt_uninit_cdclk(struct drm_i915_private *dev_priv)
> >  	bxt_set_cdclk(dev_priv, &cdclk_state);
> >  }
> >  
> > +static void cnl_cdclk_pll_update(struct drm_i915_private *dev_priv,
> > +				 struct intel_cdclk_state *cdclk_state)
> > +{
> > +	u32 val;
> > +
> > +	if (I915_READ(SKL_DSSM) & CNL_DSSM_CDCLK_PLL_REFCLK_24MHz)
> > +		cdclk_state->ref = 24000;
> > +	else
> > +		cdclk_state->ref = 19200;
> > +
> > +	cdclk_state->vco = 0;
> > +
> > +	val = I915_READ(BXT_DE_PLL_ENABLE);
> > +	if ((val & BXT_DE_PLL_PLL_ENABLE) == 0)
> > +		return;
> > +
> > +	if (WARN_ON((val & BXT_DE_PLL_LOCK) == 0))
> > +		return;
> > +
> > +	cdclk_state->vco = (val & CNL_CDCLK_PLL_RATIO_MASK) * cdclk_state->ref;
> > +}
> > +
> > +static void cnl_get_cdclk(struct drm_i915_private *dev_priv,
> > +			 struct intel_cdclk_state *cdclk_state)
> > +{
> > +	u32 divider;
> > +	int div;
> > +
> > +	cnl_cdclk_pll_update(dev_priv, cdclk_state);
> 
> The other platforms set cdclk to the ref clock here, not sure
> if it's ok to leave it uninited. With that change it looks ok:

Not sure how to address this here...
I see bxt and skl using the cdclk_state here...

> 
> Reviewed-by: Imre Deak <imre.deak@intel.com>
> 
> > +
> > +	if (cdclk_state->vco == 0)
> > +		return;
> > +
> > +	divider = I915_READ(CDCLK_CTL) & BXT_CDCLK_CD2X_DIV_SEL_MASK;
> > +
> > +	switch (divider) {
> > +	case BXT_CDCLK_CD2X_DIV_SEL_1:
> > +		div = 2;
> > +		break;
> > +	case BXT_CDCLK_CD2X_DIV_SEL_2:
> > +		div = 4;
> > +		break;
> > +	default:
> > +		MISSING_CASE(divider);
> > +		return;
> > +	}
> > +
> > +	cdclk_state->cdclk = DIV_ROUND_CLOSEST(cdclk_state->vco, div);
> > +}
> > +
> >  /**
> >   * intel_cdclk_state_compare - Determine if two CDCLK states differ
> >   * @a: first CDCLK state
> > @@ -1897,7 +1947,9 @@ void intel_init_cdclk_hooks(struct drm_i915_private *dev_priv)
> >  			skl_modeset_calc_cdclk;
> >  	}
> >  
> > -	if (IS_GEN9_BC(dev_priv))
> > +	if (IS_CANNONLAKE(dev_priv))
> > +		dev_priv->display.get_cdclk = cnl_get_cdclk;
> > +	else if (IS_GEN9_BC(dev_priv))
> >  		dev_priv->display.get_cdclk = skl_get_cdclk;
> >  	else if (IS_GEN9_LP(dev_priv))
> >  		dev_priv->display.get_cdclk = bxt_get_cdclk;
> > -- 
> > 1.9.1
> > 
> > _______________________________________________
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> > Intel-gfx@lists.freedesktop.org
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