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

[Danilo Krummrich]

On 3/19/24 10:20, Jani Nikula wrote:
> On Tue, 19 Mar 2024, Jani Nikula <jani.nikula at intel.com> 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 at intel.com>
>> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
>> Cc: Karol Herbst <kherbst at redhat.com>
>> Cc: Lyude Paul <lyude at redhat.com>
>> Cc: Danilo Krummrich <dakr at redhat.com>
>> Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
>> Signed-off-by: Jani Nikula <jani.nikula at intel.com>
>> ---
>>   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,
>