Re: [v2 5/6] i915/dp/fec: Configure the Forward Error Correction bits.

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On Fri, Oct 19, 2018 at 12:24:43PM -0700, Manasi Navare wrote:
> On Fri, Oct 19, 2018 at 09:39:11PM +0300, Ville Syrjälä wrote:
> > On Mon, Oct 15, 2018 at 02:50:36PM -0700, Anusha Srivatsa wrote:
> > > If FEC is supported, the corresponding
> > > DP_TP_CTL register bits have to be configured.
> > > 
> > > The driver has to program the FEC_ENABLE in DP_TP_CTL[30] register
> > > and wait till FEC_STATUS in DP_TP_CTL[28] is 1.
> > > Also add the warn message to make sure that the control
> > > register is already active while enabling FEC.
> > > 
> > > v2:
> > > - Change commit message. Configure fec state after
> > >   link training (Manasi, Gaurav)
> > > - Remove redundent checks (Manasi)
> > > - Remove the registers that get added automagically (Anusha)
> > > 
> > > v3: s/intel_dp_set_fec_state()/intel_dp_enable_fec_state() (Gaurav)
> > > 
> > > v4: rebased.
> > > 
> > > Cc: Gaurav K Singh <gaurav.k.singh@xxxxxxxxx>
> > > Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
> > > Cc: Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx>
> > > Cc: Manasi Navare <manasi.d.navare@xxxxxxxxx>
> > > Signed-off-by: Anusha Srivatsa <anusha.srivatsa@xxxxxxxxx>
> > > ---
> > >  drivers/gpu/drm/i915/i915_reg.h  |  2 ++
> > >  drivers/gpu/drm/i915/intel_ddi.c |  2 ++
> > >  drivers/gpu/drm/i915/intel_dp.c  | 27 +++++++++++++++++++++++++++
> > >  drivers/gpu/drm/i915/intel_drv.h |  3 ++-
> > >  4 files changed, 33 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> > > index bcde78bc0027..c8d7fdcd7823 100644
> > > --- a/drivers/gpu/drm/i915/i915_reg.h
> > > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > > @@ -9093,6 +9093,7 @@ enum skl_power_gate {
> > >  #define _DP_TP_CTL_B			0x64140
> > >  #define DP_TP_CTL(port) _MMIO_PORT(port, _DP_TP_CTL_A, _DP_TP_CTL_B)
> > >  #define  DP_TP_CTL_ENABLE			(1 << 31)
> > > +#define  DP_TP_CTL_FEC_ENABLE			(1 << 30)
> > >  #define  DP_TP_CTL_MODE_SST			(0 << 27)
> > >  #define  DP_TP_CTL_MODE_MST			(1 << 27)
> > >  #define  DP_TP_CTL_FORCE_ACT			(1 << 25)
> > > @@ -9111,6 +9112,7 @@ enum skl_power_gate {
> > >  #define _DP_TP_STATUS_A			0x64044
> > >  #define _DP_TP_STATUS_B			0x64144
> > >  #define DP_TP_STATUS(port) _MMIO_PORT(port, _DP_TP_STATUS_A, _DP_TP_STATUS_B)
> > > +#define  DP_TP_STATUS_FEC_ENABLE_LIVE		(1 << 28)
> > >  #define  DP_TP_STATUS_IDLE_DONE			(1 << 25)
> > >  #define  DP_TP_STATUS_ACT_SENT			(1 << 24)
> > >  #define  DP_TP_STATUS_MODE_STATUS_MST		(1 << 23)
> > > diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> > > index f531900165bf..67c013ea4d39 100644
> > > --- a/drivers/gpu/drm/i915/intel_ddi.c
> > > +++ b/drivers/gpu/drm/i915/intel_ddi.c
> > > @@ -2911,6 +2911,8 @@ static void intel_ddi_pre_enable_dp(struct intel_encoder *encoder,
> > >  					      DP_DECOMPRESSION_EN);
> > >  	intel_dp_sink_set_fec_ready(intel_dp, crtc_state, DP_FEC_READY);
> > >  	intel_dp_start_link_train(intel_dp);
> > > +	intel_dp_enable_fec_state(intel_dp, crtc_state);
> > 
> > This doesn't look like the correct spot. According to the spec it
> > should be after stop_link_train() (where we set DP_TP_CTL to
> > to normal).
> >
> 
> Yes I see in the display port enabling sequence page of the spec, that it says enable FEC
> after DP_TP_CTL is set to Normal. Also the FEC page says that this should be enabled only after ensuring that link training
> completed. So according to that this call should happen after
> intel_dp_stop_link_train(). 
> So yes move this to after intel_dp_stop_link_training().
> 
> > > +
> > >  	if (port != PORT_A || INTEL_GEN(dev_priv) >= 9)
> > >  		intel_dp_stop_link_train(intel_dp);
> > >  
> > > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> > > index b4e8af3142a2..b9f85502d9ff 100644
> > > --- a/drivers/gpu/drm/i915/intel_dp.c
> > > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > > @@ -3017,6 +3017,33 @@ void intel_dp_sink_set_fec_ready(struct intel_dp *intel_dp,
> > >  		DRM_DEBUG_KMS("Failed to get FEC enabled in sink\n");
> > >  }
> > >  
> > > +void intel_dp_enable_fec_state(struct intel_dp *intel_dp,
> > > +			       const struct intel_crtc_state *crtc_state)
> > > +{
> > > +	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
> > > +	struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
> > > +	enum port port = intel_dig_port->base.port;
> > > +	u32 val;
> > > +
> > > +	/* FEC support exists for DP 1.4 only */
> > > +	if (intel_dp_is_edp(intel_dp))
> > > +		return;
> > > +
> > > +	/* If Display Compression is not enabled, FEC need not be configured */
> > > +	if (!crtc_state->dsc_params.compression_enable)
> > > +		return;
> > > +
> > > +	val = I915_READ(DP_TP_CTL(port));
> > > +	val |= DP_TP_CTL_FEC_ENABLE;
> > > +	I915_WRITE(DP_TP_CTL(port), val);
> > > +
> > > +	if (intel_wait_for_register(dev_priv, DP_TP_STATUS(port),
> > > +				    DP_TP_STATUS_FEC_ENABLE_LIVE,
> > > +				    DP_TP_STATUS_FEC_ENABLE_LIVE,
> > > +				    1))
> > > +		DRM_ERROR("Timed out waiting for FEC Enable Status\n");
> > > +}
> > 
> > There is no reason to stick these into intel_dp.c when the
> > only caller is in intel_ddi.c.
> >
> 
> So may be move the set_dsc_state function also from intel_dp.c to intel_ddi.c
> Or does it make sense to move all these DSC related functions including fec to intel_dsc.c?
>  
> > We also seem to be missing platform checks. FEC doesn't appear to
> > be a thing prior to ICL. I guess the edp+compression_enable takes care
> > of this, but I think I'd rather stick a new fec_enable bool into
> > the crtc state. That way we get can add it to the state checker as well.
> >
> 
> fec_enable can be added to crtc_state->dsc_params may be?

Isn't FEC something that can be used w/o DSC too?

> 
> Manasi
>  
> > > +
> > >  /* If the sink supports it, try to set the power state appropriately */
> > >  void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode)
> > >  {
> > > diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> > > index fbc9fa06e8be..e51d612a9f42 100644
> > > --- a/drivers/gpu/drm/i915/intel_drv.h
> > > +++ b/drivers/gpu/drm/i915/intel_drv.h
> > > @@ -1532,7 +1532,6 @@ intel_encoder_current_mode(struct intel_encoder *encoder);
> > >  bool intel_port_is_tc(struct drm_i915_private *dev_priv, enum port port);
> > >  enum tc_port intel_port_to_tc(struct drm_i915_private *dev_priv,
> > >  			      enum port port);
> > > -
> > >  enum pipe intel_get_pipe_from_connector(struct intel_connector *connector);
> > >  int intel_get_pipe_from_crtc_id_ioctl(struct drm_device *dev, void *data,
> > >  				      struct drm_file *file_priv);
> > > @@ -1712,6 +1711,8 @@ void intel_dp_sink_set_decompression_state(struct intel_dp *intel_dp,
> > >  void intel_dp_sink_set_fec_ready(struct intel_dp *intel_dp,
> > >  				 const struct intel_crtc_state *crtc_state,
> > >  				 int state);
> > > +void intel_dp_enable_fec_state(struct intel_dp *intel_dp,
> > > +			       const struct intel_crtc_state *crtc_state);
> > >  void intel_dp_encoder_reset(struct drm_encoder *encoder);
> > >  void intel_dp_encoder_suspend(struct intel_encoder *intel_encoder);
> > >  void intel_dp_encoder_destroy(struct drm_encoder *encoder);
> > > -- 
> > > 2.17.1
> > 
> > -- 
> > Ville Syrjälä
> > Intel

-- 
Ville Syrjälä
Intel
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