Commit 9dbf5a4e authored by Ville Syrjälä's avatar Ville Syrjälä
Browse files

drm/i915: Provide more clues as to why MST is/is not used 



Always print out the information whether the port and sink can each
do MST. And let's include the modparam in the debug output as well.
Makes life a little less confusing when you don't have to wonder
why MST isn't kicking in.

This does cause a slight change in our behaviour towards the sink.
Previously we only read the MSTM_CAP register after passing all
the other checks. Now we will read that register regardless. Hopefully
some crazy sink doesn't get confused by a simple register read.

Signed-off-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181003184210.1306-1-ville.syrjala@linux.intel.com


Reviewed-by: default avatarDhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
parent 0fc645f3

drivers/gpu/drm/i915/intel_dp.c

+18 −15
Original line number Diff line number Diff line
@@ -4050,16 +4050,10 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp) 
}



static bool

intel_dp_can_mst(struct intel_dp *intel_dp)

intel_dp_sink_can_mst(struct intel_dp *intel_dp)

{

	u8 mstm_cap;



	if (!i915_modparams.enable_dp_mst)

		return false;



	if (!intel_dp->can_mst)

		return false;



	if (intel_dp->dpcd[DP_DPCD_REV] < 0x12)

		return false;
@@ -4069,21 +4063,30 @@ intel_dp_can_mst(struct intel_dp *intel_dp) 
	return mstm_cap & DP_MST_CAP;

}



static bool

intel_dp_can_mst(struct intel_dp *intel_dp)

{

	return i915_modparams.enable_dp_mst &&

		intel_dp->can_mst &&

		intel_dp_sink_can_mst(intel_dp);

}



static void

intel_dp_configure_mst(struct intel_dp *intel_dp)

{

	if (!i915_modparams.enable_dp_mst)

		return;

	struct intel_encoder *encoder =

		&dp_to_dig_port(intel_dp)->base;

	bool sink_can_mst = intel_dp_sink_can_mst(intel_dp);



	DRM_DEBUG_KMS("MST support? port %c: %s, sink: %s, modparam: %s\n",

		      port_name(encoder->port), yesno(intel_dp->can_mst),

		      yesno(sink_can_mst), yesno(i915_modparams.enable_dp_mst));



	if (!intel_dp->can_mst)

		return;



	intel_dp->is_mst = intel_dp_can_mst(intel_dp);



	if (intel_dp->is_mst)

		DRM_DEBUG_KMS("Sink is MST capable\n");

	else

		DRM_DEBUG_KMS("Sink is not MST capable\n");

	intel_dp->is_mst = sink_can_mst &&

		i915_modparams.enable_dp_mst;



	drm_dp_mst_topology_mgr_set_mst(&intel_dp->mst_mgr,

					intel_dp->is_mst);

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