drm/i915/dp_mst: Fix enabling pipe clock for all streams

commit afb2c4437d ("drm/i915/ddi: Push pipe clock enabling to encoders")
inadvertently stopped enabling the pipe clock for any DP-MST stream
after the first one. It also rearranged the pipe clock enabling wrt.
initial MST payload allocation step (which may or may not be a
problem, but it's contrary to the spec.).

Fix things by making the above commit truly a non-functional change.

Fixes: afb2c4437d ("drm/i915/ddi: Push pipe clock enabling to encoders")
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107365
Reported-by: Lyude Paul <lyude@redhat.com>
Reported-by: dmummenschanz@web.de
Tested-by: dmummenschanz@web.de
Tested-by: Lyude Paul <lyude@redhat.com>
Cc: Lyude Paul <lyude@redhat.com>
Cc: dmummenschanz@web.de
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180831174739.30387-1-imre.deak@intel.com

drivers/gpu/drm/i915/intel_ddi.c

@@ -2912,6 +2912,7 @@ static void intel_ddi_pre_enable_dp(struct intel_encoder *encoder,
 
 	icl_enable_phy_clock_gating(dig_port);
 
+	if (!is_mst)
 		intel_ddi_enable_pipe_clock(crtc_state);
 }
 
@@ -3015,14 +3016,14 @@ static void intel_ddi_post_disable_dp(struct intel_encoder *encoder,
 	bool is_mst = intel_crtc_has_type(old_crtc_state,
 					  INTEL_OUTPUT_DP_MST);
 
+	if (!is_mst) {
 		intel_ddi_disable_pipe_clock(old_crtc_state);
-
 		/*
 		 * Power down sink before disabling the port, otherwise we end
 		 * up getting interrupts from the sink on detecting link loss.
 		 */
-	if (!is_mst)
 		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
+	}
 
 	intel_disable_ddi_buf(encoder);
 

drivers/gpu/drm/i915/intel_dp_mst.c

@@ -166,6 +166,8 @@ static void intel_mst_post_disable_dp(struct intel_encoder *encoder,
 	struct intel_connector *connector =
 		to_intel_connector(old_conn_state->connector);
 
+	intel_ddi_disable_pipe_clock(old_crtc_state);
+
 	/* this can fail */
 	drm_dp_check_act_status(&intel_dp->mst_mgr);
 	/* and this can also fail */
@@ -249,6 +251,8 @@ static void intel_mst_pre_enable_dp(struct intel_encoder *encoder,
 	I915_WRITE(DP_TP_STATUS(port), temp);
 
 	ret = drm_dp_update_payload_part1(&intel_dp->mst_mgr);
+
+	intel_ddi_enable_pipe_clock(pipe_config);
 }
 
 static void intel_mst_enable_dp(struct intel_encoder *encoder,