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

Ville Syrjälä
2017-10-20T14:18:07Z

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 ;)

>
>
> > ---
> > 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