Re: [PATCH v2 09/21] drm/i915/dp: Pass atomic state to link training function

[Imre Deak <imre.deak@intel.com>]

On Thu, May 23, 2024 at 05:41:17PM +0300, Ville Syrjälä wrote:
> On Mon, May 20, 2024 at 09:58:07PM +0300, Imre Deak wrote:
> > From: Imre Deak <imre.deak@gmail.com>
> > 
> > The next patch adds sending a modeset-retry uevent after a link training
> > failure to all MST connectors on link. This requires the atomic state,
> > so pass it to intel_dp_start_link_train(). In case of SST where
> > retraining still happens by calling this function directly instead of a
> > modeset commit the atomic state is not available and NULL is passed
> > instead. This is ok, since in this case the encoder's only DP connector
> > is available from intel_dp->attached_connector not requiring the atomic
> > state.
> > 
> > Signed-off-by: Imre Deak <imre.deak@gmail.com>
> > ---
> >  drivers/gpu/drm/i915/display/g4x_dp.c                 | 2 +-
> >  drivers/gpu/drm/i915/display/intel_ddi.c              | 6 +++---
> >  drivers/gpu/drm/i915/display/intel_dp.c               | 2 +-
> >  drivers/gpu/drm/i915/display/intel_dp_link_training.c | 4 +++-
> >  drivers/gpu/drm/i915/display/intel_dp_link_training.h | 4 +++-
> >  5 files changed, 11 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/g4x_dp.c b/drivers/gpu/drm/i915/display/g4x_dp.c
> > index 4363e32a834df..0d7424a7581e6 100644
> > --- a/drivers/gpu/drm/i915/display/g4x_dp.c
> > +++ b/drivers/gpu/drm/i915/display/g4x_dp.c
> > @@ -707,7 +707,7 @@ static void intel_enable_dp(struct intel_atomic_state *state,
> >  	intel_dp_configure_protocol_converter(intel_dp, pipe_config);
> >  	intel_dp_check_frl_training(intel_dp);
> >  	intel_dp_pcon_dsc_configure(intel_dp, pipe_config);
> > -	intel_dp_start_link_train(intel_dp, pipe_config);
> > +	intel_dp_start_link_train(state, intel_dp, pipe_config);
> >  	intel_dp_stop_link_train(intel_dp, pipe_config);
> >  }
> >  
> > diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
> > index 86358ec27e685..58e57a7704811 100644
> > --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> > +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> > @@ -2586,7 +2586,7 @@ static void mtl_ddi_pre_enable_dp(struct intel_atomic_state *state,
> >  	 *     Pattern, wait for 5 idle patterns (DP_TP_STATUS Min_Idles_Sent)
> >  	 *     (timeout after 800 us)
> >  	 */
> > -	intel_dp_start_link_train(intel_dp, crtc_state);
> > +	intel_dp_start_link_train(state, intel_dp, crtc_state);
> >  
> >  	/* 6.n Set DP_TP_CTL link training to Normal */
> >  	if (!is_trans_port_sync_mode(crtc_state))
> > @@ -2728,7 +2728,7 @@ static void tgl_ddi_pre_enable_dp(struct intel_atomic_state *state,
> >  	 *     Pattern, wait for 5 idle patterns (DP_TP_STATUS Min_Idles_Sent)
> >  	 *     (timeout after 800 us)
> >  	 */
> > -	intel_dp_start_link_train(intel_dp, crtc_state);
> > +	intel_dp_start_link_train(state, intel_dp, crtc_state);
> >  
> >  	/* 7.k Set DP_TP_CTL link training to Normal */
> >  	if (!is_trans_port_sync_mode(crtc_state))
> > @@ -2795,7 +2795,7 @@ static void hsw_ddi_pre_enable_dp(struct intel_atomic_state *state,
> >  						   to_intel_connector(conn_state->connector),
> >  						   crtc_state);
> >  	intel_dp_sink_set_fec_ready(intel_dp, crtc_state, true);
> > -	intel_dp_start_link_train(intel_dp, crtc_state);
> > +	intel_dp_start_link_train(state, intel_dp, crtc_state);
> >  	if ((port != PORT_A || DISPLAY_VER(dev_priv) >= 9) &&
> >  	    !is_trans_port_sync_mode(crtc_state))
> >  		intel_dp_stop_link_train(intel_dp, crtc_state);
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> > index 7c824c5a13346..1f0b7cceea2dc 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > @@ -5214,7 +5214,7 @@ int intel_dp_retrain_link(struct intel_encoder *encoder,
> >  
> >  		intel_dp_check_frl_training(intel_dp);
> >  		intel_dp_pcon_dsc_configure(intel_dp, crtc_state);
> > -		intel_dp_start_link_train(intel_dp, crtc_state);
> > +		intel_dp_start_link_train(NULL, intel_dp, crtc_state);
> 
> I was going to suggest s/crtc_state/crtc/ for this, but the state==NULL
> definitiely makes that impossible. I think we need to document each and
> every function where the atomic state may be NULL and thus needs to be
> passed the crtc_state as well. Otherwise someone (probably me) is likely
> going to attempt some cleanups which will then explode, or someone will
> just attempt to dig out something from the full atomic state (eg.
> state->base.dev).

This is meant to be a temporary solution, for maybe a few weeks after
this gets merged after which retraining should be switched over to be a
modeset in all cases; but agreed it's better to document that in
intel_dp_start_link_train(), will add that.

> 
> >  		intel_dp_stop_link_train(intel_dp, crtc_state);
> >  		break;
> >  	}
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.c b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> > index e804f0b801c02..4f60daa97407d 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> > @@ -1453,6 +1453,7 @@ intel_dp_128b132b_link_train(struct intel_dp *intel_dp,
> >  
> >  /**
> >   * intel_dp_start_link_train - start link training
> > + * @state: Atomic state
> >   * @intel_dp: DP struct
> >   * @crtc_state: state for CRTC attached to the encoder
> >   *
> > @@ -1461,7 +1462,8 @@ intel_dp_128b132b_link_train(struct intel_dp *intel_dp,
> >   * fails.
> >   * After calling this function intel_dp_stop_link_train() must be called.
> >   */
> > -void intel_dp_start_link_train(struct intel_dp *intel_dp,
> > +void intel_dp_start_link_train(struct intel_atomic_state *state,
> > +			       struct intel_dp *intel_dp,
> >  			       const struct intel_crtc_state *crtc_state)
> >  {
> >  	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.h b/drivers/gpu/drm/i915/display/intel_dp_link_training.h
> > index 19836a8a4f904..f658230960333 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp_link_training.h
> > +++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.h
> > @@ -8,6 +8,7 @@
> >  
> >  #include <drm/display/drm_dp_helper.h>
> >  
> > +struct intel_atomic_state;
> >  struct intel_crtc_state;
> >  struct intel_dp;
> >  
> > @@ -25,7 +26,8 @@ void intel_dp_program_link_training_pattern(struct intel_dp *intel_dp,
> >  void intel_dp_set_signal_levels(struct intel_dp *intel_dp,
> >  				const struct intel_crtc_state *crtc_state,
> >  				enum drm_dp_phy dp_phy);
> > -void intel_dp_start_link_train(struct intel_dp *intel_dp,
> > +void intel_dp_start_link_train(struct intel_atomic_state *state,
> > +			       struct intel_dp *intel_dp,
> >  			       const struct intel_crtc_state *crtc_state);
> >  void intel_dp_stop_link_train(struct intel_dp *intel_dp,
> >  			      const struct intel_crtc_state *crtc_state);
> > -- 
> > 2.43.3
> 
> -- 
> Ville Syrjälä
> Intel