[Intel-gfx] [PATCH 31/67] drm/i915/cnl: Allow dynamic cdclk changes on CNL

[Pandiyan, Dhinakaran]

On Mon, 2017-06-05 at 19:55 +0300, Ville Syrjälä wrote:
> On Mon, Jun 05, 2017 at 04:41:07PM +0000, Vivi, Rodrigo wrote:
> > On Mon, 2017-06-05 at 18:22 +0300, Imre Deak wrote:
> > > On Thu, Apr 06, 2017 at 12:15:27PM -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.
> > > > 
> > > > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > > > Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
> > > > ---
> > > >  drivers/gpu/drm/i915/intel_cdclk.c | 54 ++++++++++++++++++++++++++++++++++++--
> > > >  1 file changed, 52 insertions(+), 2 deletions(-)
> > > > 
> > > > diff --git a/drivers/gpu/drm/i915/intel_cdclk.c b/drivers/gpu/drm/i915/intel_cdclk.c
> > > > index f9ba1e7..a8c254b 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)
> > > >  {
> > > > @@ -1640,7 +1650,7 @@ 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);
> > > > @@ -1928,6 +1938,40 @@ 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);
> > > 
> > > The spec says not to set CDCLK to 168MHz if audio is used with 96MHz
> > > BCLK, what's the plan to add that constraint? At least there could be a
> > > TODO: here.
> > 
> > That's a good question.
> > Do we have ways to know the audio freq?
> > Or we need to add few extra hooks?
> > And agree, at least a TODO or FIXME here is needed while we dont have a
> > clear path.
> 
> bdw_adjust_min_pipe_pixel_rate() just assumes 96MHz. There was some
> discussion on the topic, and I found some register that possibly could
> tell us something. But the best solution would probably involve querying
> it from the audio driver.
> 

The last time I checked with the audio folks, the driver does not change
the BCLK freq. and the default is 96 MHz. 


> > 
> > > 
> > > > +
> > > > +	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;
> > > > @@ -1959,7 +2003,9 @@ 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;
> > > >  
> > > > @@ -2158,6 +2204,10 @@ 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
> > > > 
> > > > _______________________________________________
> > > > Intel-gfx mailing list
> > > > Intel-gfx at lists.freedesktop.org
> > > > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
> > 
>