[Intel-gfx] [PATCH v2 1/4] drm/i915/icl: Assign Master slave crtc links for Transcoder Port Sync

[Manasi Navare]

Need some suggestions on what could be stored in slave_crtc_state to point to the master,
See my comments/questions inline

On Tue, Apr 23, 2019 at 08:48:58AM -0700, Manasi Navare wrote:
> In case of tiled displays when the two tiles are sent across two CRTCs
> over two separate DP SST connectors, we need a mechanism to synchronize
> the two CRTCs and their corresponding transcoders.
> So use the master-slave mode where there is one master corresponding
> to last horizontal and vertical tile that needs to be genlocked with
> all other slave tiles.
> This patch identifies saves the master CRTC pointer in all the slave
> CRTC states. This pointer is needed to select the master CRTC/transcoder
> while configuring transcoder port sync for the corresponding slaves.
> 
> v2:
> * Move this to intel_mode_set_pipe_config(Jani N, Ville)
> * Use slave_bitmask to save associated slaves in master crtc state (Ville)
> 
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> Cc: Matt Roper <matthew.d.roper at intel.com>
> Signed-off-by: Manasi Navare <manasi.d.navare at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 89 ++++++++++++++++++++++++++++
>  drivers/gpu/drm/i915/intel_drv.h     |  6 ++
>  2 files changed, 95 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index b276345779e6..92dea2231499 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -11316,6 +11316,86 @@ static int icl_check_nv12_planes(struct intel_crtc_state *crtc_state)
>  	return 0;
>  }
>  
> +static int icl_add_genlock_crtcs(struct drm_crtc *crtc,
> +				 struct intel_crtc_state *crtc_state,
> +				 struct drm_atomic_state *state)
> +{
> +	struct drm_i915_private *dev_priv = to_i915(crtc_state->base.crtc->dev);
> +	struct drm_connector *master_connector, *connector;
> +	struct drm_connector_state *connector_state;
> +	struct drm_connector_list_iter conn_iter;
> +	struct drm_crtc *master_crtc = NULL;
> +	struct drm_crtc_state *master_crtc_state;
> +	int i, tile_group_id;
> +
> +	if (INTEL_GEN(dev_priv) < 11)
> +		return 0;
> +
> +	/*
> +	 * In case of tiled displays there could be one or more slaves but there is
> +	 * only one master. Lets make the CRTC used by the connector corresponding
> +	 * to the last horizonal and last vertical tile a master/genlock CRTC.
> +	 * All the other CRTCs corresponding to other tiles of the same Tile group
> +	 * are the slave CRTCs and hold a pointer to their genlock CRTC.
> +	 */
> +	for_each_new_connector_in_state(state, connector, connector_state, i) {
> +		if (connector_state->crtc != crtc)
> +			continue;
> +		if (!connector->has_tile)
> +			continue;
> +		if (connector->tile_h_loc == connector->num_h_tile - 1 &&
> +		    connector->tile_v_loc == connector->num_v_tile - 1)
> +			continue;
> +		crtc_state->master_crtc = NULL;
> +		tile_group_id = connector->tile_group->id;
> +		drm_connector_list_iter_begin(&dev_priv->drm, &conn_iter);
> +		drm_for_each_connector_iter(master_connector, &conn_iter) {
> +			struct drm_connector_state *master_conn_state = NULL;
> +
> +			if (!master_connector->has_tile)
> +				continue;
> +			if (master_connector->tile_h_loc != master_connector->num_h_tile - 1 ||
> +			    master_connector->tile_v_loc != master_connector->num_v_tile - 1)
> +				continue;
> +			if (master_connector->tile_group->id != tile_group_id)
> +				continue;
> +
> +			master_conn_state = drm_atomic_get_connector_state(state,
> +									   master_connector);
> +			if (IS_ERR(master_conn_state)) {
> +				drm_connector_list_iter_end(&conn_iter);
> +				return PTR_ERR(master_conn_state);
> +			}
> +			if (master_conn_state->crtc) {
> +				master_crtc = master_conn_state->crtc;
> +				break;
> +			}
> +		}
> +		drm_connector_list_iter_end(&conn_iter);
> +
> +		if (!master_crtc) {
> +			DRM_DEBUG_KMS("Could not add Master CRTC for Slave CRTC %d\n",
> +				      connector_state->crtc->base.id);
> +			return -EINVAL;
> +		}
> +
> +		master_crtc_state = drm_atomic_get_crtc_state(state,
> +							      master_crtc);
> +		if (IS_ERR(master_crtc_state))
> +			return PTR_ERR(master_crtc_state);
> +
> +		crtc_state->master_crtc = to_intel_crtc(master_crtc);

This stores a pointer to master_crtc which is used to obtain the master_crtc_state in crtc_enable
and obtain cpu_transcoder from that to configure master_select in TRANS PORT SYNC register
However, during the HW state readout we will read this register back for the slave to obtain the
master transcoder and I dont really have a clear path to find the master crtc from master transcoder
in order to do pipe_config_compare() in verify_crtc_state() which is currently causing the Pipe mismatch errors

Any suggestions on how this can be fixed? This assignment happens very early on before modeset_pipe_config, 
so I dont believe I can use master_crtc_state->cpu_transcoder to obtain master transcoder.

Manasi

> +		to_intel_crtc_state(master_crtc_state)->trans_port_sync_slaves |=
> +			BIT(to_intel_crtc(crtc)->pipe);
> +		DRM_DEBUG_KMS("Master CRTC = %d added for Slave CRTC = %d\n, slave bitmast = %d",
> +			      master_crtc->base.id,
> +			      crtc_state->base.crtc->base.id,
> +			      to_intel_crtc_state(master_crtc_state)->trans_port_sync_slaves);
> +	}
> +
> +	return 0;
> +}
> +
>  static int intel_crtc_atomic_check(struct drm_crtc *crtc,
>  				   struct drm_crtc_state *crtc_state)
>  {
> @@ -11795,6 +11875,9 @@ clear_intel_crtc_state(struct intel_crtc_state *crtc_state)
>  	if (IS_G4X(dev_priv) ||
>  	    IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
>  		saved_state->wm = crtc_state->wm;
> +	if (INTEL_GEN(dev_priv) >= 11)
> +		saved_state->trans_port_sync_slaves =
> +			crtc_state->trans_port_sync_slaves;
>  
>  	/* Keep base drm_crtc_state intact, only clear our extended struct */
>  	BUILD_BUG_ON(offsetof(struct intel_crtc_state, base));
> @@ -11888,6 +11971,12 @@ intel_modeset_pipe_config(struct drm_crtc *crtc,
>  	drm_mode_set_crtcinfo(&pipe_config->base.adjusted_mode,
>  			      CRTC_STEREO_DOUBLE);
>  
> +	ret = icl_add_genlock_crtcs(crtc, pipe_config, state);
> +	if (ret) {
> +		DRM_DEBUG_KMS("\n8K Debug: Cannot assign genlock crtcs");
> +		return ret;
> +	}
> +
>  	/* Pass our mode to the connectors and the CRTC to give them a chance to
>  	 * adjust it according to limitations or connector properties, and also
>  	 * a chance to reject the mode entirely.
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index a38b9cff5cd0..8ae9cb662e28 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -1082,6 +1082,12 @@ struct intel_crtc_state {
>  
>  	/* Forward Error correction State */
>  	bool fec_enable;
> +
> +	/* Pointer to master crtc in case of tiled displays */
> +	struct intel_crtc *master_crtc;
> +
> +	/* Bitmask to indicate slaves attached */
> +	u8 trans_port_sync_slaves;
>  };
>  
>  struct intel_crtc {
> -- 
> 2.19.1
>