Re: [PATCH 8/8] drm/i915: Adjust system agent voltage on CNL if required by DDI ports

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

On Fri, Oct 20, 2017 at 05:18:04PM +0300, Ville Syrjälä wrote:
> On Thu, Oct 19, 2017 at 04:54:56PM -0700, Rodrigo Vivi wrote:
> > 
> > On Wed, Oct 18, 2017 at 08:48:25PM +0000, Ville Syrjala wrote:
> > > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > 
> > > On CNL we may need to bump up the system agent voltage not only due
> > > to CDCLK but also when driving DDI port with a sufficiently high clock.
> > > To that end start tracking the minimum acceptable voltage for each crtc.
> > > We do the tracking via crtcs because we don't have any kind of encoder
> > > state. Also there's no downside to doing it this way, and it matches how
> > > we track cdclk requirements on account of pixel rate.
> > > 
> > > Cc: Mika Kahola <mika.kahola@intel.com>
> > > Cc: Manasi Navare <manasi.d.navare@intel.com>
> > > Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> > > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > 
> > Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> > 
> > Tested-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> > (Although I didn't find cases where I could force a higher voltage level,
> > everything works well on CNL with this.)
> 
> For a quick test hack you could just reduce the port clock limit in
> intel_ddi_compute_min_voltage() to something you can reach.
> 
> So probably something like:
> 1. enable one pipe with low port clock that can operate at min voltage
> 2. enable a second pipe with higher port clock that need max voltage
> 3. stare at the logs to make sure we ramp up the voltage correctly,
>    and that the first pipe didn't undergo a modeset needlessly
> 
> Oh, and I guess you'd have to make sure that both pipes can operate at
> the same low cdclk value so that cdclk changes won't interfere with
> your observations.
> 
> Actually this kind of hack could be tested on any platform, assuming
> they will tolerate voltage changes with pipes on. I guess I can give
> it a quick whirl on my SKL here and see if the smoke escapes ;)

OK, quick test here found some bugs. I sent a v2 which seems to do the
right thing on my SKL with the aforementioned hacks in place.

> 
> > 
> > 
> > > ---
> > >  drivers/gpu/drm/i915/i915_drv.h      |  2 ++
> > >  drivers/gpu/drm/i915/intel_cdclk.c   | 34 +++++++++++++++++++++++++++++++++-
> > >  drivers/gpu/drm/i915/intel_ddi.c     | 13 +++++++++++++
> > >  drivers/gpu/drm/i915/intel_display.c |  6 ++++++
> > >  drivers/gpu/drm/i915/intel_dp_mst.c  |  5 +++++
> > >  drivers/gpu/drm/i915/intel_drv.h     |  6 ++++++
> > >  6 files changed, 65 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> > > index d3ac58dc275f..185711a852b0 100644
> > > --- a/drivers/gpu/drm/i915/i915_drv.h
> > > +++ b/drivers/gpu/drm/i915/i915_drv.h
> > > @@ -2415,6 +2415,8 @@ struct drm_i915_private {
> > >  	unsigned int active_crtcs;
> > >  	/* minimum acceptable cdclk for each pipe */
> > >  	int min_cdclk[I915_MAX_PIPES];
> > > +	/* minimum acceptable voltage for each pipe */
> > > +	u8 min_voltage[I915_MAX_PIPES];
> > >  
> > >  	int dpio_phy_iosf_port[I915_NUM_PHYS_VLV];
> > >  
> > > diff --git a/drivers/gpu/drm/i915/intel_cdclk.c b/drivers/gpu/drm/i915/intel_cdclk.c
> > > index 795a18f64c4c..035c44858908 100644
> > > --- a/drivers/gpu/drm/i915/intel_cdclk.c
> > > +++ b/drivers/gpu/drm/i915/intel_cdclk.c
> > > @@ -1666,6 +1666,13 @@ static void cnl_set_cdclk(struct drm_i915_private *dev_priv,
> > >  	mutex_unlock(&dev_priv->pcu_lock);
> > >  
> > >  	intel_update_cdclk(dev_priv);
> > > +
> > > +	/*
> > > +	 * Can't read this out :( Can't rely on .get_cdclk() since it
> > > +	 * doesn't know about DDI voltage requirements. So let's just
> > > +	 * assume everything is as expected.
> > > +	 */
> > > +	dev_priv->cdclk.hw.voltage = cdclk_state->voltage;
> > >  }
> > >  
> > >  static int cnl_cdclk_pll_vco(struct drm_i915_private *dev_priv, int cdclk)
> > > @@ -1935,6 +1942,29 @@ static int intel_compute_min_cdclk(struct drm_atomic_state *state)
> > >  	return min_cdclk;
> > >  }
> > >  
> > > +static u8 intel_compute_min_voltage(struct intel_atomic_state *state)
> > > +{
> > > +	struct drm_i915_private *dev_priv = to_i915(state->base.dev);
> > > +	struct intel_crtc *crtc;
> > > +	struct intel_crtc_state *crtc_state;
> > > +	u8 min_voltage;
> > > +	int i;
> > > +	enum pipe pipe;
> > > +
> > > +	memcpy(state->min_voltage, dev_priv->min_voltage,
> > > +	       sizeof(state->min_voltage));
> > > +
> > > +	for_each_new_intel_crtc_in_state(state, crtc, crtc_state, i)
> > > +		state->min_voltage[i] = crtc_state->min_voltage;
> > > +
> > > +	min_voltage = 0;
> > > +	for_each_pipe(dev_priv, pipe)
> > > +		min_voltage = max(state->min_voltage[pipe],
> > > +				  min_voltage);
> > > +
> > > +	return min_voltage;
> > > +}
> > > +
> > >  static int vlv_modeset_calc_cdclk(struct drm_atomic_state *state)
> > >  {
> > >  	struct drm_i915_private *dev_priv = to_i915(state->dev);
> > > @@ -2091,7 +2121,9 @@ static int cnl_modeset_calc_cdclk(struct drm_atomic_state *state)
> > >  
> > >  	intel_state->cdclk.logical.vco = vco;
> > >  	intel_state->cdclk.logical.cdclk = cdclk;
> > > -	intel_state->cdclk.logical.voltage = cnl_calc_voltage(cdclk);
> > > +	intel_state->cdclk.logical.voltage =
> > > +		max(cnl_calc_voltage(cdclk),
> > > +		    intel_compute_min_voltage(intel_state));
> > >  
> > >  	if (!intel_state->active_crtcs) {
> > >  		cdclk = cnl_calc_cdclk(0);
> > > diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> > > index adf51b328844..f02e3c2f4ad2 100644
> > > --- a/drivers/gpu/drm/i915/intel_ddi.c
> > > +++ b/drivers/gpu/drm/i915/intel_ddi.c
> > > @@ -2525,6 +2525,15 @@ bool intel_ddi_is_audio_enabled(struct drm_i915_private *dev_priv,
> > >  	return false;
> > >  }
> > >  
> > > +void intel_ddi_compute_min_voltage(struct drm_i915_private *dev_priv,
> > > +				   struct intel_crtc_state *crtc_state)
> > > +{
> > > +	if (INTEL_GEN(dev_priv) >= 10 && crtc_state->port_clock > 594000)
> > > +		crtc_state->min_voltage = 2;
> > > +	else
> > > +		crtc_state->min_voltage = 0;
> > > +}
> > > +
> > >  void intel_ddi_get_config(struct intel_encoder *encoder,
> > >  			  struct intel_crtc_state *pipe_config)
> > >  {
> > > @@ -2624,6 +2633,8 @@ void intel_ddi_get_config(struct intel_encoder *encoder,
> > >  	if (IS_GEN9_LP(dev_priv))
> > >  		pipe_config->lane_lat_optim_mask =
> > >  			bxt_ddi_phy_get_lane_lat_optim_mask(encoder);
> > > +
> > > +	intel_ddi_compute_min_voltage(dev_priv, pipe_config);
> > >  }
> > >  
> > >  static bool intel_ddi_compute_config(struct intel_encoder *encoder,
> > > @@ -2650,6 +2661,8 @@ static bool intel_ddi_compute_config(struct intel_encoder *encoder,
> > >  			bxt_ddi_phy_calc_lane_lat_optim_mask(encoder,
> > >  							     pipe_config->lane_count);
> > >  
> > > +	intel_ddi_compute_min_voltage(dev_priv, pipe_config);
> > > +
> > >  	return ret;
> > >  
> > >  }
> > > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > > index 32e7cca52da2..7d293ecb51c4 100644
> > > --- a/drivers/gpu/drm/i915/intel_display.c
> > > +++ b/drivers/gpu/drm/i915/intel_display.c
> > > @@ -5938,6 +5938,7 @@ static void intel_crtc_disable_noatomic(struct drm_crtc *crtc,
> > >  
> > >  	dev_priv->active_crtcs &= ~(1 << intel_crtc->pipe);
> > >  	dev_priv->min_cdclk[intel_crtc->pipe] = 0;
> > > +	dev_priv->min_voltage[intel_crtc->pipe] = 0;
> > >  }
> > >  
> > >  /*
> > > @@ -11304,6 +11305,8 @@ intel_pipe_config_compare(struct drm_i915_private *dev_priv,
> > >  	PIPE_CONF_CHECK_CLOCK_FUZZY(base.adjusted_mode.crtc_clock);
> > >  	PIPE_CONF_CHECK_CLOCK_FUZZY(port_clock);
> > >  
> > > +	PIPE_CONF_CHECK_I(min_voltage);
> > > +
> > >  #undef PIPE_CONF_CHECK_X
> > >  #undef PIPE_CONF_CHECK_I
> > >  #undef PIPE_CONF_CHECK_P
> > > @@ -12532,6 +12535,8 @@ static int intel_atomic_commit(struct drm_device *dev,
> > >  	if (intel_state->modeset) {
> > >  		memcpy(dev_priv->min_cdclk, intel_state->min_cdclk,
> > >  		       sizeof(intel_state->min_cdclk));
> > > +		memcpy(dev_priv->min_voltage, intel_state->min_voltage,
> > > +		       sizeof(intel_state->min_voltage));
> > >  		dev_priv->active_crtcs = intel_state->active_crtcs;
> > >  		dev_priv->cdclk.logical = intel_state->cdclk.logical;
> > >  		dev_priv->cdclk.actual = intel_state->cdclk.actual;
> > > @@ -15042,6 +15047,7 @@ static void intel_modeset_readout_hw_state(struct drm_device *dev)
> > >  		}
> > >  
> > >  		dev_priv->min_cdclk[crtc->pipe] = min_cdclk;
> > > +		dev_priv->min_voltage[crtc->pipe] = crtc_state->min_voltage;
> > >  
> > >  		intel_pipe_config_sanity_check(dev_priv, crtc_state);
> > >  	}
> > > diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
> > > index 772521440a9f..6c1da88b5fef 100644
> > > --- a/drivers/gpu/drm/i915/intel_dp_mst.c
> > > +++ b/drivers/gpu/drm/i915/intel_dp_mst.c
> > > @@ -34,6 +34,7 @@ static bool intel_dp_mst_compute_config(struct intel_encoder *encoder,
> > >  					struct intel_crtc_state *pipe_config,
> > >  					struct drm_connector_state *conn_state)
> > >  {
> > > +	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> > >  	struct intel_dp_mst_encoder *intel_mst = enc_to_mst(&encoder->base);
> > >  	struct intel_digital_port *intel_dig_port = intel_mst->primary;
> > >  	struct intel_dp *intel_dp = &intel_dig_port->dp;
> > > @@ -87,6 +88,8 @@ static bool intel_dp_mst_compute_config(struct intel_encoder *encoder,
> > >  
> > >  	pipe_config->dp_m_n.tu = slots;
> > >  
> > > +	intel_ddi_compute_min_voltage(dev_priv, pipe_config);
> > > +
> > >  	return true;
> > >  }
> > >  
> > > @@ -307,6 +310,8 @@ static void intel_dp_mst_enc_get_config(struct intel_encoder *encoder,
> > >  	intel_dp_get_m_n(crtc, pipe_config);
> > >  
> > >  	intel_ddi_clock_get(&intel_dig_port->base, pipe_config);
> > > +
> > > +	intel_ddi_compute_min_voltage(dev_priv, pipe_config);
> > >  }
> > >  
> > >  static int intel_dp_mst_get_ddc_modes(struct drm_connector *connector)
> > > diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> > > index 765a737700c5..002894b13d69 100644
> > > --- a/drivers/gpu/drm/i915/intel_drv.h
> > > +++ b/drivers/gpu/drm/i915/intel_drv.h
> > > @@ -386,6 +386,8 @@ struct intel_atomic_state {
> > >  	unsigned int active_crtcs;
> > >  	/* minimum acceptable cdclk for each pipe */
> > >  	int min_cdclk[I915_MAX_PIPES];
> > > +	/* minimum acceptable voltage for each pipe */
> > > +	u8 min_voltage[I915_MAX_PIPES];
> > >  
> > >  	struct intel_shared_dpll_state shared_dpll[I915_NUM_PLLS];
> > >  
> > > @@ -739,6 +741,8 @@ struct intel_crtc_state {
> > >  	 */
> > >  	uint8_t lane_lat_optim_mask;
> > >  
> > > +	u8 min_voltage;
> > > +
> > >  	/* Panel fitter controls for gen2-gen4 + VLV */
> > >  	struct {
> > >  		u32 control;
> > > @@ -1294,6 +1298,8 @@ void intel_ddi_clock_get(struct intel_encoder *encoder,
> > >  			 struct intel_crtc_state *pipe_config);
> > >  void intel_ddi_set_vc_payload_alloc(const struct intel_crtc_state *crtc_state,
> > >  				    bool state);
> > > +void intel_ddi_compute_min_voltage(struct drm_i915_private *dev_priv,
> > > +				   struct intel_crtc_state *crtc_state);
> > >  u32 bxt_signal_levels(struct intel_dp *intel_dp);
> > >  uint32_t ddi_signal_levels(struct intel_dp *intel_dp);
> > >  u8 intel_ddi_dp_voltage_max(struct intel_encoder *encoder);
> > > -- 
> > > 2.13.6
> > > 
> 
> -- 
> Ville Syrjälä
> Intel OTC

-- 
Ville Syrjälä
Intel OTC
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