drm/i915: Extract intel_ddi_post_disable_hdmi_or_sst()

Extract the "not-MST" stuff from intel_ddi_post_disable() so that
the whole thing isn't so cluttered.

The bigjoiner slave handling was outside of the !MST check,
but it really should have been inside it as its the counterpart
to the master handling inside the check. So we pull that
in as well. There is no functional change here as we don't
currently support bigjoiner+MST anyway.

v2: Rebase
v3: Actually extract the slave code as claimed in
    the commit message (presumably a rebase fail in v2)
Tested-by: Vidya Srinivas <vidya.srinivas@intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240409163502.29633-2-ville.syrjala@linux.intel.com

drivers/gpu/drm/i915/display/intel_ddi.c

@@ -3091,7 +3091,7 @@ static void intel_ddi_post_disable_hdmi(struct intel_atomic_state *state,
 	intel_dp_dual_mode_set_tmds_output(intel_hdmi, false);
 }
 
-static void intel_ddi_post_disable(struct intel_atomic_state *state,
+static void intel_ddi_post_disable_hdmi_or_sst(struct intel_atomic_state *state,
 					       struct intel_encoder *encoder,
 					       const struct intel_crtc_state *old_crtc_state,
 					       const struct drm_connector_state *old_conn_state)
@@ -3099,7 +3099,6 @@ static void intel_ddi_post_disable(struct intel_atomic_state *state,
 	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
 	struct intel_crtc *slave_crtc;
 
-	if (!intel_crtc_has_type(old_crtc_state, INTEL_OUTPUT_DP_MST)) {
 	intel_crtc_vblank_off(old_crtc_state);
 
 	intel_disable_transcoder(old_crtc_state);
@@ -3112,7 +3111,6 @@ static void intel_ddi_post_disable(struct intel_atomic_state *state,
 		skl_scaler_disable(old_crtc_state);
 	else
 		ilk_pfit_disable(old_crtc_state);
-	}
 
 	for_each_intel_crtc_in_pipe_mask(&dev_priv->drm, slave_crtc,
 					 intel_crtc_bigjoiner_slave_pipes(old_crtc_state)) {
@@ -3124,6 +3122,16 @@ static void intel_ddi_post_disable(struct intel_atomic_state *state,
 		intel_dsc_disable(old_slave_crtc_state);
 		skl_scaler_disable(old_slave_crtc_state);
 	}
+}
+
+static void intel_ddi_post_disable(struct intel_atomic_state *state,
+				   struct intel_encoder *encoder,
+				   const struct intel_crtc_state *old_crtc_state,
+				   const struct drm_connector_state *old_conn_state)
+{
+	if (!intel_crtc_has_type(old_crtc_state, INTEL_OUTPUT_DP_MST))
+		intel_ddi_post_disable_hdmi_or_sst(state, encoder, old_crtc_state,
+						   old_conn_state);
 
 	/*
 	 * When called from DP MST code: