Re: [RESEND v3 1/6] drm/mst: read sideband messaging cap

[Danilo Krummrich <dakr@xxxxxxxxxx>]

On 3/19/24 10:20, Jani Nikula wrote:
> On Tue, 19 Mar 2024, Jani Nikula <jani.nikula@xxxxxxxxx> wrote:
> > Amend drm_dp_read_mst_cap() to return an enum, indicating "SST", "SST
> > with sideband messaging", or "MST". Modify all call sites to take the
> > new return value into account.
>
> drm-misc and nouveau maintainers, ack for merging this via drm-intel,
> please?

Sure, please go ahead.

Thanks,
Danilo

> BR,
> Jani.
>
>
>
> > v2:
> > - Rename enumerators (Ville)
> >
> > Cc: Arun R Murthy <arun.r.murthy@xxxxxxxxx>
> > Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> > Cc: Karol Herbst <kherbst@xxxxxxxxxx>
> > Cc: Lyude Paul <lyude@xxxxxxxxxx>
> > Cc: Danilo Krummrich <dakr@xxxxxxxxxx>
> > Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> > Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
> > ---
> >   drivers/gpu/drm/display/drm_dp_mst_topology.c | 20 ++++++++++------
> >   drivers/gpu/drm/i915/display/intel_dp.c       |  4 ++--
> >   drivers/gpu/drm/nouveau/nouveau_dp.c          |  2 +-
> >   include/drm/display/drm_dp_mst_helper.h       | 23 ++++++++++++++++++-
> >   4 files changed, 38 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > index 03d528209426..c193be3577f7 100644
> > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > @@ -3608,24 +3608,30 @@ fixed20_12 drm_dp_get_vc_payload_bw(const struct drm_dp_mst_topology_mgr *mgr,
> >   EXPORT_SYMBOL(drm_dp_get_vc_payload_bw);
> >   
> >   /**
> > - * drm_dp_read_mst_cap() - check whether or not a sink supports MST
> > + * drm_dp_read_mst_cap() - Read the sink's MST mode capability
> >    * @aux: The DP AUX channel to use
> >    * @dpcd: A cached copy of the DPCD capabilities for this sink
> >    *
> > - * Returns: %True if the sink supports MST, %false otherwise
> > + * Returns: enum drm_dp_mst_mode to indicate MST mode capability
> >    */
> > -bool drm_dp_read_mst_cap(struct drm_dp_aux *aux,
> > -			 const u8 dpcd[DP_RECEIVER_CAP_SIZE])
> > +enum drm_dp_mst_mode drm_dp_read_mst_cap(struct drm_dp_aux *aux,
> > +					 const u8 dpcd[DP_RECEIVER_CAP_SIZE])
> >   {
> >   	u8 mstm_cap;
> >   
> >   	if (dpcd[DP_DPCD_REV] < DP_DPCD_REV_12)
> > -		return false;
> > +		return DRM_DP_SST;
> >   
> >   	if (drm_dp_dpcd_readb(aux, DP_MSTM_CAP, &mstm_cap) != 1)
> > -		return false;
> > +		return DRM_DP_SST;
> > +
> > +	if (mstm_cap & DP_MST_CAP)
> > +		return DRM_DP_MST;
> > +
> > +	if (mstm_cap & DP_SINGLE_STREAM_SIDEBAND_MSG)
> > +		return DRM_DP_SST_SIDEBAND_MSG;
> >   
> > -	return mstm_cap & DP_MST_CAP;
> > +	return DRM_DP_SST;
> >   }
> >   EXPORT_SYMBOL(drm_dp_read_mst_cap);
> >   
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> > index af7ca00e9bc0..91c42949ac7e 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > @@ -4046,7 +4046,7 @@ intel_dp_can_mst(struct intel_dp *intel_dp)
> >   
> >   	return i915->display.params.enable_dp_mst &&
> >   		intel_dp_mst_source_support(intel_dp) &&
> > -		drm_dp_read_mst_cap(&intel_dp->aux, intel_dp->dpcd);
> > +		drm_dp_read_mst_cap(&intel_dp->aux, intel_dp->dpcd) == DRM_DP_MST;
> >   }
> >   
> >   static void
> > @@ -4055,7 +4055,7 @@ intel_dp_configure_mst(struct intel_dp *intel_dp)
> >   	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> >   	struct intel_encoder *encoder =
> >   		&dp_to_dig_port(intel_dp)->base;
> > -	bool sink_can_mst = drm_dp_read_mst_cap(&intel_dp->aux, intel_dp->dpcd);
> > +	bool sink_can_mst = drm_dp_read_mst_cap(&intel_dp->aux, intel_dp->dpcd) == DRM_DP_MST;
> >   
> >   	drm_dbg_kms(&i915->drm,
> >   		    "[ENCODER:%d:%s] MST support: port: %s, sink: %s, modparam: %s\n",
> > diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c b/drivers/gpu/drm/nouveau/nouveau_dp.c
> > index 7de7707ec6a8..fb06ee17d9e5 100644
> > --- a/drivers/gpu/drm/nouveau/nouveau_dp.c
> > +++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
> > @@ -181,7 +181,7 @@ nouveau_dp_probe_dpcd(struct nouveau_connector *nv_connector,
> >   	if (nouveau_mst) {
> >   		mstm = outp->dp.mstm;
> >   		if (mstm)
> > -			mstm->can_mst = drm_dp_read_mst_cap(aux, dpcd);
> > +			mstm->can_mst = drm_dp_read_mst_cap(aux, dpcd) == DRM_DP_MST;
> >   	}
> >   
> >   	if (nouveau_dp_has_sink_count(connector, outp)) {
> > diff --git a/include/drm/display/drm_dp_mst_helper.h b/include/drm/display/drm_dp_mst_helper.h
> > index 3ae88a383a41..cbcb49cb6a46 100644
> > --- a/include/drm/display/drm_dp_mst_helper.h
> > +++ b/include/drm/display/drm_dp_mst_helper.h
> > @@ -817,7 +817,28 @@ int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr,
> >   
> >   void drm_dp_mst_topology_mgr_destroy(struct drm_dp_mst_topology_mgr *mgr);
> >   
> > -bool drm_dp_read_mst_cap(struct drm_dp_aux *aux, const u8 dpcd[DP_RECEIVER_CAP_SIZE]);
> > +/**
> > + * enum drm_dp_mst_mode - sink's MST mode capability
> > + */
> > +enum drm_dp_mst_mode {
> > +	/**
> > +	 * @DRM_DP_SST: The sink does not support MST nor single stream sideband
> > +	 * messaging.
> > +	 */
> > +	DRM_DP_SST,
> > +	/**
> > +	 * @DRM_DP_MST: Sink supports MST, more than one stream and single
> > +	 * stream sideband messaging.
> > +	 */
> > +	DRM_DP_MST,
> > +	/**
> > +	 * @DRM_DP_SST_SIDEBAND_MSG: Sink supports only one stream and single
> > +	 * stream sideband messaging.
> > +	 */
> > +	DRM_DP_SST_SIDEBAND_MSG,
> > +};
> > +
> > +enum drm_dp_mst_mode drm_dp_read_mst_cap(struct drm_dp_aux *aux, const u8 dpcd[DP_RECEIVER_CAP_SIZE]);
> >   int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool mst_state);
> >   
> >   int drm_dp_mst_hpd_irq_handle_event(struct drm_dp_mst_topology_mgr *mgr,