drm/i915/display/icl: Enable TRANSCODER PORT SYNC for tiled displays across separate ports

In case of tiled displays where different tiles are displayed across
different ports, we need to synchronize the transcoders involved.
This patch implements the transcoder port sync feature for
synchronizing one master transcoder with one or more slave
transcoders. This is only enbaled in slave transcoder
and the master transcoder is unaware that it is operating
in this mode.
This has been tested with tiled display connected to ICL.

v7:
* Rebase on Maarten's patches
v6:
* Use master_trans +1 and address missing trans_edp case (Ville)
v5:
* Add TRANSCODER_D case and MISSING_CASE (Maarten)
v4:
Rebase
v3:
* Check of DP_MST moved to atomic_check (Maarten)
v2:
* Do not use RMW, just write to the register in commit (Jani N)

Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191018172725.1338-2-manasi.d.navare@intel.com

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

@@ -4405,6 +4405,36 @@ static void icl_set_pipe_chicken(struct intel_crtc *crtc)
 	I915_WRITE(PIPE_CHICKEN(pipe), tmp);
 }
 
+static void icl_enable_trans_port_sync(const struct intel_crtc_state *crtc_state)
+{
+	struct intel_crtc *crtc = to_intel_crtc(crtc_state->base.crtc);
+	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
+	u32 trans_ddi_func_ctl2_val;
+	u8 master_select;
+
+	/*
+	 * Configure the master select and enable Transcoder Port Sync for
+	 * Slave CRTCs transcoder.
+	 */
+	if (crtc_state->master_transcoder == INVALID_TRANSCODER)
+		return;
+
+	if (crtc_state->master_transcoder == TRANSCODER_EDP)
+		master_select = 0;
+	else
+		master_select = crtc_state->master_transcoder + 1;
+
+	/* Set the master select bits for Tranascoder Port Sync */
+	trans_ddi_func_ctl2_val = (PORT_SYNC_MODE_MASTER_SELECT(master_select) &
+				   PORT_SYNC_MODE_MASTER_SELECT_MASK) <<
+		PORT_SYNC_MODE_MASTER_SELECT_SHIFT;
+	/* Enable Transcoder Port Sync */
+	trans_ddi_func_ctl2_val |= PORT_SYNC_MODE_ENABLE;
+
+	I915_WRITE(TRANS_DDI_FUNC_CTL2(crtc_state->cpu_transcoder),
+		   trans_ddi_func_ctl2_val);
+}
+
 static void intel_fdi_normal_train(struct intel_crtc *crtc)
 {
 	struct drm_device *dev = crtc->base.dev;
@@ -6429,6 +6459,9 @@ static void haswell_crtc_enable(struct intel_crtc_state *pipe_config,
 	if (!transcoder_is_dsi(cpu_transcoder))
 		intel_set_pipe_timings(pipe_config);
 
+	if (INTEL_GEN(dev_priv) >= 11)
+		icl_enable_trans_port_sync(pipe_config);
+
 	intel_set_pipe_src_size(pipe_config);
 
 	if (cpu_transcoder != TRANSCODER_EDP &&