[PATCH 12/13] drm/dp_mst: Add DSC enablement helpers to DRM

[<mikita.lipski-5C7GfCeVMHo@public.gmane.org>]

From: Mikita Lipski <mikita.lipski@amd.com>

Adding the following elements to add MST DSC support to DRM:

- dsc_enable boolean flag to drm_dp_vcpi_allocation structure to signal,
which port got DSC enabled

- function drm_dp_helper_update_vcpi_slots_for_dsc allows reallocation
of newly recalculated VCPI slots and raises dsc_enable flag on the port.

- function drm_dp_mst_update_dsc_crtcs is called in drm_dp_mst_atomic_check,
its purpose is to iterate through all the ports in the topology and set
mode_changed flag on crtc if DSC has been enabled.

Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Lyude Paul <lyude@redhat.com>
Signed-off-by: Mikita Lipski <mikita.lipski@amd.com>
---
 drivers/gpu/drm/drm_dp_mst_topology.c | 103 +++++++++++++++++++++++++-
 include/drm/drm_dp_mst_helper.h       |   4 +
 2 files changed, 106 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index d5df02315e14..4f2f09fe32f8 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -73,6 +73,7 @@ static bool drm_dp_validate_guid(struct drm_dp_mst_topology_mgr *mgr,
 static int drm_dp_mst_register_i2c_bus(struct drm_dp_aux *aux);
 static void drm_dp_mst_unregister_i2c_bus(struct drm_dp_aux *aux);
 static void drm_dp_mst_kick_tx(struct drm_dp_mst_topology_mgr *mgr);
+static void drm_dp_mst_update_dsc_crtcs(struct drm_dp_mst_topology_state *mst_state);
 
 #define DP_STR(x) [DP_ ## x] = #x
 
@@ -3293,6 +3294,65 @@ int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
 }
 EXPORT_SYMBOL(drm_dp_atomic_find_vcpi_slots);
 
+/**
+ * drm_dp_helper_update_vcpi_slots_for_dsc() - Update VCPI slots with new on the state
+ *
+ * @state: global atomic state
+ * @port: port to find vcpi slots
+ * @pbn: updated bandwidth required for the mode in PBN
+ *
+ * Function reallocates VCPI slots to the @port by calling
+ * drm_dp_atomic_find_vcpi_slots. The assumption is that VCPI slots
+ * have already been allocated and this is second call overwritting
+ * initial values. After the VCPI is allocated dsc_enable flag is set to
+ * true for atomic check.
+ *
+ * It is driver's responsibility to call this function after it decides
+ * to enable DSC.
+ *
+ * See also:
+ * drm_dp_mst_update_dsc_crtcs()
+ *
+ * Returns:
+ * Total slots in the atomic state assigned for this port, or a negative error
+ * code if the port no longer exists or vcpi slots haven't been assigned.
+ */
+int drm_dp_helper_update_vcpi_slots_for_dsc(struct drm_atomic_state *state,
+					    struct drm_dp_mst_port *port,
+					    int pbn)
+{
+	struct drm_dp_mst_topology_state *topology_state;
+	struct drm_dp_vcpi_allocation *pos;
+	bool found = false;
+	int vcpi = 0;
+
+	topology_state = drm_atomic_get_mst_topology_state(state, port->mgr);
+
+	if (IS_ERR(topology_state))
+		return PTR_ERR(topology_state);
+
+	list_for_each_entry(pos, &topology_state->vcpis, next) {
+		if (pos->port == port) {
+			found = true;
+			break;
+		}
+	}
+
+	if (!found || !pos->vcpi)
+		return -EINVAL;
+
+	vcpi = drm_dp_atomic_find_vcpi_slots(state, port->mgr,
+					     port, pbn);
+
+	if (vcpi < 0)
+		return -EINVAL;
+
+	pos->dsc_enable = true;
+
+	return vcpi;
+}
+
+EXPORT_SYMBOL(drm_dp_helper_update_vcpi_slots_for_dsc);
 /**
  * drm_dp_atomic_release_vcpi_slots() - Release allocated vcpi slots
  * @state: global atomic state
@@ -3871,6 +3931,46 @@ drm_dp_mst_atomic_check_topology_state(struct drm_dp_mst_topology_mgr *mgr,
 	return 0;
 }
 
+/**
+ * drm_dp_mst_update_dsc_crtcs - Set mode change flag on CRTCs which
+ * just got DSC enabled
+ * @state: Pointer to the new &struct drm_dp_mst_topology_state
+ *
+ * Itearate through all the ports in MST topology to check if DSC
+ * has been enabled on any of them. Set mode_changed to true on
+ * crtc state that just got DSC enabled.
+ *
+ * See also:
+ * drm_dp_helper_update_vcpi_slots_for_dsc()
+ */
+static void
+drm_dp_mst_update_dsc_crtcs(struct drm_dp_mst_topology_state *mst_state)
+{
+	struct drm_dp_vcpi_allocation *pos;
+	struct drm_dp_mst_port *port;
+	struct drm_connector_state *conn_state;
+	struct drm_crtc *crtc;
+	struct drm_crtc_state *crtc_state;
+
+	list_for_each_entry(pos, &mst_state->vcpis, next) {
+
+		port = pos->port;
+		conn_state = drm_atomic_get_connector_state(mst_state->base.state,
+							    port->connector);
+		crtc = conn_state->crtc;
+		if (!crtc)
+			continue;
+
+		crtc_state = drm_atomic_get_crtc_state(mst_state->base.state, crtc);
+		if (port->vcpi.vcpi == pos->vcpi)
+			continue;
+
+		if (pos->dsc_enable) {
+			crtc_state->mode_changed = true;
+			pos->dsc_enable = false;
+		}
+	}
+}
 /**
  * drm_dp_mst_atomic_check - Check that the new state of an MST topology in an
  * atomic update is valid
@@ -3887,9 +3987,9 @@ drm_dp_mst_atomic_check_topology_state(struct drm_dp_mst_topology_mgr *mgr,
  * See also:
  * drm_dp_atomic_find_vcpi_slots()
  * drm_dp_atomic_release_vcpi_slots()
- *
  * Returns:
  *
+ *
  * 0 if the new state is valid, negative error code otherwise.
  */
 int drm_dp_mst_atomic_check(struct drm_atomic_state *state)
@@ -3902,6 +4002,7 @@ int drm_dp_mst_atomic_check(struct drm_atomic_state *state)
 		ret = drm_dp_mst_atomic_check_topology_state(mgr, mst_state);
 		if (ret)
 			break;
+		drm_dp_mst_update_dsc_crtcs(mst_state);
 	}
 
 	return ret;
diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h
index 4cf738545dfb..185e29895f5f 100644
--- a/include/drm/drm_dp_mst_helper.h
+++ b/include/drm/drm_dp_mst_helper.h
@@ -431,6 +431,7 @@ struct drm_dp_payload {
 struct drm_dp_vcpi_allocation {
 	struct drm_dp_mst_port *port;
 	int vcpi;
+	bool dsc_enable;
 	struct list_head next;
 };
 
@@ -662,6 +663,9 @@ int __must_check
 drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
 			      struct drm_dp_mst_topology_mgr *mgr,
 			      struct drm_dp_mst_port *port, int pbn);
+int drm_dp_helper_update_vcpi_slots_for_dsc(struct drm_atomic_state *state,
+					    struct drm_dp_mst_port *port,
+					    int pbn);
 int __must_check
 drm_dp_atomic_release_vcpi_slots(struct drm_atomic_state *state,
 				 struct drm_dp_mst_topology_mgr *mgr,
-- 
2.17.1

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