[PATCH v2 4/6] drm/i915/mst: use the MST mode detected previously

[Jani Nikula]

Drop the duplicate read of DP_MSTM_CAP DPCD register, and the duplicate
logic for choosing MST mode, and store the chosen mode in struct
intel_dp. Rename intel_dp_configure_mst() to intel_dp_mst_configure()
while at it.

Cc: Arun R Murthy <arun.r.mur...@intel.com>
Cc: Ville Syrjälä <ville.syrj...@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nik...@intel.com>
---
 .../drm/i915/display/intel_display_types.h    |  1 +
 drivers/gpu/drm/i915/display/intel_dp.c       | 23 ++++++++-----------
 2 files changed, 11 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h 
b/drivers/gpu/drm/i915/display/intel_display_types.h
index 01eb6e4e6049..4a8440a3a812 100644
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -1780,6 +1780,7 @@ struct intel_dp {
 
        bool is_mst;
        int active_mst_links;
+       enum drm_dp_mst_mode mst_detect;
 
        /* connector directly attached - won't be use for modeset in mst world 
*/
        struct intel_connector *attached_connector;
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c 
b/drivers/gpu/drm/i915/display/intel_dp.c
index 007cb2a04e38..72e91322e310 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -4039,11 +4039,10 @@ intel_dp_mst_detect(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;
        enum drm_dp_mst_mode sink_mst_mode;
-       enum drm_dp_mst_mode mst_detect;
 
        sink_mst_mode = drm_dp_read_mst_cap(&intel_dp->aux, intel_dp->dpcd);
 
-       mst_detect = intel_dp_mst_mode_choose(intel_dp, sink_mst_mode);
+       intel_dp->mst_detect = intel_dp_mst_mode_choose(intel_dp, 
sink_mst_mode);
 
        drm_dbg_kms(&i915->drm,
                    "[ENCODER:%d:%s] MST support: port: %s, sink: %s, modparam: 
%s -> enable: %s\n",
@@ -4051,25 +4050,23 @@ intel_dp_mst_detect(struct intel_dp *intel_dp)
                    str_yes_no(intel_dp_mst_source_support(intel_dp)),
                    intel_dp_mst_mode_str(sink_mst_mode),
                    str_yes_no(i915->display.params.enable_dp_mst),
-                   intel_dp_mst_mode_str(mst_detect));
+                   intel_dp_mst_mode_str(intel_dp->mst_detect));
 
-       return mst_detect != DRM_DP_SST;
+       return intel_dp->mst_detect != DRM_DP_SST;
 }
 
 static void
-intel_dp_configure_mst(struct intel_dp *intel_dp)
+intel_dp_mst_configure(struct intel_dp *intel_dp)
 {
-       struct drm_i915_private *i915 = dp_to_i915(intel_dp);
-       bool sink_can_mst = drm_dp_read_mst_cap(&intel_dp->aux, intel_dp->dpcd) 
== DRM_DP_MST;
-
        if (!intel_dp_mst_source_support(intel_dp))
                return;
 
-       intel_dp->is_mst = sink_can_mst &&
-               i915->display.params.enable_dp_mst;
+       intel_dp->is_mst = intel_dp->mst_detect != DRM_DP_SST;
+
+       drm_dp_mst_topology_mgr_set_mst(&intel_dp->mst_mgr, intel_dp->is_mst);
 
-       drm_dp_mst_topology_mgr_set_mst(&intel_dp->mst_mgr,
-                                       intel_dp->is_mst);
+       /* Avoid stale info on the next detect cycle. */
+       intel_dp->mst_detect = DRM_DP_SST;
 }
 
 static bool
@@ -5739,7 +5736,7 @@ intel_dp_detect(struct drm_connector *connector,
 
        intel_dp_detect_dsc_caps(intel_dp, intel_connector);
 
-       intel_dp_configure_mst(intel_dp);
+       intel_dp_mst_configure(intel_dp);
 
        /*
         * TODO: Reset link params when switching to MST mode, until MST
-- 
2.39.2