Re: [PATCH 1/2] drm/i915/icl: Assign genlock CRTC pointer in all slave CRTC states for tiled displays

[Jani Nikula <jani.nikula@linux.intel.com>]

On Thu, 21 Mar 2019, Manasi Navare <manasi.d.navare@intel.com> 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.
>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: Matt Roper <matthew.d.roper@intel.com>
> Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 84 ++++++++++++++++++++++++++++
>  drivers/gpu/drm/i915/intel_drv.h     |  3 +
>  2 files changed, 87 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 8ff7aa8cb3cf..9980a4ed8c9c 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -11281,6 +11281,86 @@ static int icl_check_nv12_planes(struct intel_crtc_state *crtc_state)
>  	return 0;
>  }
>  
> +static int icl_add_genlock_crtcs(struct drm_device *dev,
> +				 struct drm_atomic_state *state)
> +{
> +	struct drm_i915_private *dev_priv = to_i915(dev);
> +	struct drm_connector *genlock_connector, *connector;
> +	struct drm_connector_state *connector_state;
> +	struct drm_connector_list_iter conn_iter;
> +	struct drm_crtc *genlock_crtc = NULL;
> +	struct drm_crtc_state *genlock_crtc_state;
> +	struct intel_crtc_state *slave_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)
> +			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;
> +		slave_crtc_state = to_intel_crtc_state(
> +			drm_atomic_get_new_crtc_state(state,
> +						      connector_state->crtc));
> +		slave_crtc_state->genlock_crtc = NULL;
> +		tile_group_id = connector->tile_group->id;
> +		drm_connector_list_iter_begin(dev, &conn_iter);
> +		drm_for_each_connector_iter(genlock_connector, &conn_iter) {
> +			struct drm_connector_state *genlock_conn_state = NULL;
> +
> +			if (!genlock_connector->has_tile)
> +				continue;
> +			if (genlock_connector->tile_h_loc != genlock_connector->num_h_tile - 1 ||
> +			    genlock_connector->tile_v_loc != genlock_connector->num_v_tile - 1)
> +				continue;
> +			if (genlock_connector->tile_group->id != tile_group_id)
> +				continue;
> +
> +			genlock_conn_state = drm_atomic_get_connector_state(state,
> +									    genlock_connector);
> +			if (IS_ERR(genlock_conn_state)) {
> +				drm_connector_list_iter_end(&conn_iter);
> +				return PTR_ERR(genlock_conn_state);
> +			}
> +			if (genlock_conn_state->crtc) {
> +				genlock_crtc = genlock_conn_state->crtc;
> +				break;
> +			}
> +		}
> +		drm_connector_list_iter_end(&conn_iter);

The above loop would benefit from being abstracted to a separate
function. "find genlock master based on tile info"

I wonder if it would work to have each relevant encoder ->compute_config
hook look for its genlock master instead of adding another top level
loop.

BR,
Jani.


> +
> +		if (!genlock_crtc) {
> +			DRM_DEBUG_KMS("Could not add Genlock CRTC for Slave CRTC %d\n",
> +				      connector_state->crtc->base.id);
> +			return -EINVAL;
> +		}
> +
> +		genlock_crtc_state = drm_atomic_get_crtc_state(state,
> +							       genlock_crtc);
> +		if (IS_ERR(genlock_crtc_state))
> +			return PTR_ERR(genlock_crtc_state);
> +
> +		slave_crtc_state->genlock_crtc = to_intel_crtc(genlock_crtc);
> +		DRM_DEBUG_KMS("Genlock CRTC = %d added for Slave CRTC = %d\n",
> +			      genlock_crtc->base.id,
> +			      slave_crtc_state->base.crtc->base.id);
> +	}
> +
> +	return 0;
> +}
> +
>  static int intel_crtc_atomic_check(struct drm_crtc *crtc,
>  				   struct drm_crtc_state *crtc_state)
>  {
> @@ -13098,6 +13178,10 @@ static int intel_atomic_check(struct drm_device *dev,
>  	if (ret)
>  		return ret;
>  
> +	ret = icl_add_genlock_crtcs(dev, state);
> +	if (ret)
> +		return ret;
> +
>  	for_each_oldnew_crtc_in_state(state, crtc, old_crtc_state, crtc_state, i) {
>  		struct intel_crtc_state *pipe_config =
>  			to_intel_crtc_state(crtc_state);
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 4d7ae579fc92..b41728946b73 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -1074,6 +1074,9 @@ struct intel_crtc_state {
>  
>  	/* Forward Error correction State */
>  	bool fec_enable;
> +
> +	/* Pointer to master/genlock crtc in case of tiled displays */
> +	struct intel_crtc *genlock_crtc;
>  };
>  
>  struct intel_crtc {

-- 
Jani Nikula, Intel Open Source Graphics Center
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