Re: [PATCH 04/17] drm/i915/cnl: Allow dynamic cdclk changes on CNL

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

On Fri, Jun 09, 2017 at 10:02:09PM +0300, Imre Deak wrote:
> On Fri, Jun 09, 2017 at 05:34:55PM +0300, Ville Syrjälä wrote:
> > On Thu, Jun 08, 2017 at 03:03:13PM -0700, Rodrigo Vivi wrote:
> > > All the low level cdclk bits are present, so let's add the required
> > > hooks to reconfigure cdclk on the fly.
> > > 
> > > v2: Rebase due to cnl_sanitize_cdclk()
> > > v3: Rebased by Rodrigo on top of Ville's cdclk rework.
> > > v4: Rebase moving cnl_calc_cdclk up to follow same order
> > >     as previous platforms.
> > > v2: Squash drm/i915/cnl: Adjust min pixel rate. to address
> > >     the current limitation where CDCLK cannot be set to 168MHz
> > >     if audio is used with 96MHz. (Imre)
> > > 
> > > Cc: Imre Deak <imre.deak@intel.com>
> > > Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
> > > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> > > 
> > > Cannonlake also needs to adjust the minimal pixel rate
> > > as gen9 platforms. Specially for the Azalia audio case.
> > > 
> > > Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
> > > Cc: Sanyog Kale <sanyog.r.kale@intel.com>
> > > Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/intel_cdclk.c | 56 ++++++++++++++++++++++++++++++++++++--
> > >  1 file changed, 53 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/intel_cdclk.c b/drivers/gpu/drm/i915/intel_cdclk.c
> > > index 35a1432..1d7cfc5 100644
> > > --- a/drivers/gpu/drm/i915/intel_cdclk.c
> > > +++ b/drivers/gpu/drm/i915/intel_cdclk.c
> > > @@ -1400,6 +1400,16 @@ void bxt_uninit_cdclk(struct drm_i915_private *dev_priv)
> > >  	bxt_set_cdclk(dev_priv, &cdclk_state);
> > >  }
> > >  
> > > +static int cnl_calc_cdclk(int max_pixclk)
> > > +{
> > > +	if (max_pixclk > 336000)
> > > +		return 528000;
> > > +	else if (max_pixclk > 168000)
> > > +		return 336000;
> > > +	else
> > > +		return 168000;
> > > +}
> > > +
> > >  static void cnl_cdclk_pll_update(struct drm_i915_private *dev_priv,
> > >  				 struct intel_cdclk_state *cdclk_state)
> > >  {
> > > @@ -1641,7 +1651,7 @@ void cnl_init_cdclk(struct drm_i915_private *dev_priv)
> > >  
> > >  	cdclk_state = dev_priv->cdclk.hw;
> > >  
> > > -	cdclk_state.cdclk = 168000;
> > > +	cdclk_state.cdclk = cnl_calc_cdclk(0);
> > >  	cdclk_state.vco = cnl_cdclk_pll_vco(dev_priv, cdclk_state.cdclk);
> > >  
> > >  	cnl_set_cdclk(dev_priv, &cdclk_state);
> > > @@ -1768,7 +1778,7 @@ static int intel_max_pixel_rate(struct drm_atomic_state *state)
> > >  
> > >  		pixel_rate = crtc_state->pixel_rate;
> > >  
> > > -		if (IS_BROADWELL(dev_priv) || IS_GEN9(dev_priv))
> > > +		if (IS_BROADWELL(dev_priv) || INTEL_GEN(dev_priv) >= 9)
> > >  			pixel_rate =
> > >  				bdw_adjust_min_pipe_pixel_rate(crtc_state,
> > >  							       pixel_rate);
> > 
> > I think you might also have to adjust some of the clock limits
> > within bdw_adjust_min_pipe_pixel_rate().
> 
> Yes, we missed this. The DP/HBR2/4-lanes/audio workaround on CNL is the
> same as on GLK. So in bdw_adjust_min_pipe_pixel_rate() we could use the
> same limits as on GLK, except I don't understand the 2x multiplier there
> in
> 
> pixel_rate = max(2 * 316800, pixel_rate);
> 
> and
> 
> pixel_rate = max(2 * 2 * 96000, pixel_rate);
> 
> This pixel_rate value will be compared against CDCLK limit values in
> glk_calc_cdclk()

It's going to compare against 2*cdclk. But that doesn't mean it isn't
extremely confusing. To make it more sane, I think we should probably
s/min_pixclk/min_cdclk/ and actually track the "min acceptable cdclk"
rather than "the pixel rate corresponding to the min acceptable cdclk".

> not CD2XCLK limit values. Removing the 2x multiplier
> from the above pixel_rate values wouldn't change anything on GLK AFAICS
> and it would allow us to use the same code to calculate these on GLK
> and CNL (and simplify the second pixel_rate calculation).
> 
> --Imre
> 
> > 
> > > @@ -1929,6 +1939,40 @@ static int bxt_modeset_calc_cdclk(struct drm_atomic_state *state)
> > >  	return 0;
> > >  }
> > >  
> > > +static int cnl_modeset_calc_cdclk(struct drm_atomic_state *state)
> > > +{
> > > +	struct drm_i915_private *dev_priv = to_i915(state->dev);
> > > +	struct intel_atomic_state *intel_state =
> > > +		to_intel_atomic_state(state);
> > > +	int max_pixclk = intel_max_pixel_rate(state);
> > > +	int cdclk, vco;
> > > +
> > > +	cdclk = cnl_calc_cdclk(max_pixclk);
> > > +	vco = cnl_cdclk_pll_vco(dev_priv, cdclk);
> > > +
> > > +	if (cdclk > dev_priv->max_cdclk_freq) {
> > > +		DRM_DEBUG_KMS("requested cdclk (%d kHz) exceeds max (%d kHz)\n",
> > > +			      cdclk, dev_priv->max_cdclk_freq);
> > > +		return -EINVAL;
> > > +	}
> > > +
> > > +	intel_state->cdclk.logical.vco = vco;
> > > +	intel_state->cdclk.logical.cdclk = cdclk;
> > > +
> > > +	if (!intel_state->active_crtcs) {
> > > +		cdclk = cnl_calc_cdclk(0);
> > > +		vco = cnl_cdclk_pll_vco(dev_priv, cdclk);
> > > +
> > > +		intel_state->cdclk.actual.vco = vco;
> > > +		intel_state->cdclk.actual.cdclk = cdclk;
> > > +	} else {
> > > +		intel_state->cdclk.actual =
> > > +			intel_state->cdclk.logical;
> > > +	}
> > > +
> > > +	return 0;
> > > +}
> > > +
> > >  static int intel_compute_max_dotclk(struct drm_i915_private *dev_priv)
> > >  {
> > >  	int max_cdclk_freq = dev_priv->max_cdclk_freq;
> > > @@ -1960,7 +2004,9 @@ static int intel_compute_max_dotclk(struct drm_i915_private *dev_priv)
> > >   */
> > >  void intel_update_max_cdclk(struct drm_i915_private *dev_priv)
> > >  {
> > > -	if (IS_GEN9_BC(dev_priv)) {
> > > +	if (IS_CANNONLAKE(dev_priv)) {
> > > +		dev_priv->max_cdclk_freq = 528000;
> > > +	} else if (IS_GEN9_BC(dev_priv)) {
> > >  		u32 limit = I915_READ(SKL_DFSM) & SKL_DFSM_CDCLK_LIMIT_MASK;
> > >  		int max_cdclk, vco;
> > >  
> > > @@ -2157,6 +2203,10 @@ void intel_init_cdclk_hooks(struct drm_i915_private *dev_priv)
> > >  		dev_priv->display.set_cdclk = skl_set_cdclk;
> > >  		dev_priv->display.modeset_calc_cdclk =
> > >  			skl_modeset_calc_cdclk;
> > > +	} else if (IS_CANNONLAKE(dev_priv)) {
> > > +		dev_priv->display.set_cdclk = cnl_set_cdclk;
> > > +		dev_priv->display.modeset_calc_cdclk =
> > > +			cnl_modeset_calc_cdclk;
> > >  	}
> > >  
> > >  	if (IS_CANNONLAKE(dev_priv))
> > > -- 
> > > 1.9.1
> > 
> > -- 
> > Ville Syrjälä
> > Intel OTC

-- 
Ville Syrjälä
Intel OTC
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