[PATCH 24/30] drm/i915/dp_mst: Enable MST DSC decompression for all streams

[Imre Deak]

Enable DSC decompression for all streams. In particular atm if a sink is
connected to a last branch device that is downstream of the first branch
device connected to the source, decompression is not enabled for it.
Similarly it's not enabled if the sink supports this with the last
branch device passing through the compressed stream to it.

Enable DSC in the above cases as well. Since last branch devices may
handle the decompression for multiple ports, toggling DSC needs to be
refcounted, add this using the DSC AUX device as a reference.

Signed-off-by: Imre Deak <imre.deak at intel.com>
---
 .../drm/i915/display/intel_display_types.h    |  1 +
 drivers/gpu/drm/i915/display/intel_dp.c       |  3 +
 drivers/gpu/drm/i915/display/intel_dp_mst.c   | 57 ++++++++++++-------
 3 files changed, 42 insertions(+), 19 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
index 409dbf8a2a1cd..b2744a9b4678c 100644
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -626,6 +626,7 @@ struct intel_connector {
 		u8 fec_capability;
 
 		u8 dsc_hblank_expansion_quirk:1;
+		u8 dsc_decompression_enabled:1;
 	} dp;
 
 	/* Work struct to schedule a uevent on link train failure */
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 763fcb95f82af..aea613a49553e 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -1403,6 +1403,7 @@ static bool intel_dp_supports_dsc(const struct intel_connector *connector,
 		return false;
 
 	return intel_dsc_source_support(crtc_state) &&
+		connector->dp.dsc_decompression_aux &&
 		drm_dp_sink_supports_dsc(connector->dp.dsc_dpcd);
 }
 
@@ -2966,6 +2967,8 @@ intel_dp_sink_set_dsc_decompression(struct intel_connector *connector,
 		drm_dbg_kms(&i915->drm,
 			    "Failed to %s sink decompression state\n",
 			    str_enable_disable(enable));
+
+	connector->dp.dsc_decompression_enabled = enable;
 }
 
 static void
diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
index 8ef3a2611207c..9f4894c2e7860 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -660,6 +660,39 @@ intel_dp_mst_atomic_topology_check(struct intel_connector *connector,
 	return ret;
 }
 
+static int intel_dp_mst_dsc_aux_use_count(struct intel_atomic_state *state,
+					  const struct intel_connector *connector)
+{
+	struct intel_connector *connector_iter;
+	struct intel_digital_connector_state *conn_state;
+	int use_count = 0;
+	int i;
+
+	for_each_new_intel_connector_in_state(state, connector_iter, conn_state, i) {
+		if (connector_iter->mst_port != connector->mst_port ||
+		    !conn_state->base.crtc)
+			continue;
+
+		if (!connector_iter->dp.dsc_decompression_enabled)
+			continue;
+
+		if (connector_iter->dp.dsc_decompression_aux ==
+		    connector->dp.dsc_decompression_aux)
+			use_count++;
+	}
+
+	return use_count;
+}
+
+static void intel_dp_mst_sink_set_decompression_state(struct intel_atomic_state *state,
+						      struct intel_connector *connector,
+						      const struct intel_crtc_state *crtc_state,
+						      bool enable)
+{
+	if (!intel_dp_mst_dsc_aux_use_count(state, connector))
+		intel_dp_sink_set_decompression_state(connector, crtc_state, enable);
+}
+
 static int
 intel_dp_mst_atomic_check(struct drm_connector *connector,
 			  struct drm_atomic_state *_state)
@@ -730,12 +763,7 @@ static void intel_mst_disable_dp(struct intel_atomic_state *state,
 
 	intel_audio_codec_disable(encoder, old_crtc_state, old_conn_state);
 
-	if (intel_dp->active_mst_links == 1) /* last stream ? */
-		/*
-		 * TODO: disable decompression for all streams/in any MST ports, not
-		 * only in the first downstream branch device.
-		 */
-		intel_dp_sink_set_decompression_state(connector, old_crtc_state, false);
+	intel_dp_mst_sink_set_decompression_state(state, connector, old_crtc_state, false);
 }
 
 static void intel_mst_post_disable_dp(struct intel_atomic_state *state,
@@ -890,15 +918,11 @@ static void intel_mst_pre_enable_dp(struct intel_atomic_state *state,
 
 	drm_dp_send_power_updown_phy(&intel_dp->mst_mgr, connector->port, true);
 
-	if (first_mst_stream) {
-		/*
-		 * TODO: enable decompression for all streams/in any MST ports, not
-		 * only in the first downstream branch device.
-		 */
-		intel_dp_sink_set_decompression_state(connector, pipe_config, true);
+	intel_dp_mst_sink_set_decompression_state(state, connector, pipe_config, true);
+
+	if (first_mst_stream)
 		dig_port->base.pre_enable(state, &dig_port->base,
 						pipe_config, NULL);
-	}
 
 	intel_dp->active_mst_links++;
 
@@ -1350,12 +1374,7 @@ static struct drm_connector *intel_dp_add_mst_connector(struct drm_dp_mst_topolo
 
 	drm_connector_helper_add(connector, &intel_dp_mst_connector_helper_funcs);
 
-	/*
-	 * TODO: set the AUX for the actual MST port decompressing the stream.
-	 * At the moment the driver only supports enabling this globally in the
-	 * first downstream MST branch, via intel_dp's (root port) AUX.
-	 */
-	intel_connector->dp.dsc_decompression_aux = &intel_dp->aux;
+	intel_connector->dp.dsc_decompression_aux = drm_dp_mst_dsc_aux_for_port(port);
 	intel_dp_mst_read_decompression_port_dsc_caps(intel_dp, intel_connector);
 	intel_connector->dp.dsc_hblank_expansion_quirk =
 		detect_dsc_hblank_expansion_quirk(intel_connector);
-- 
2.39.2