[PATCH v6 10/13] drm/dp_mst: Add DSC enablement helpers to DRM

[mikita.lipski at amd.com]

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

Adding a helper function to be called by
drivers outside of DRM to enable DSC on
the MST ports.

Function is called to recalculate VCPI allocation
if DSC is enabled and raise the DSC flag to enable.
In case of disabling DSC the flag is set to false
and recalculation of VCPI slots is expected to be done
in encoder's atomic_check.

v2: squash separate functions into one and call it per
port

Cc: Harry Wentland <harry.wentland at amd.com>
Cc: Lyude Paul <lyude at redhat.com>
Signed-off-by: Mikita Lipski <mikita.lipski at amd.com>
---
 drivers/gpu/drm/drm_dp_mst_topology.c | 76 +++++++++++++++++++++++++++
 include/drm/drm_dp_mst_helper.h       |  5 ++
 2 files changed, 81 insertions(+)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index d5df02315e14..86e20dbf3cce 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -3871,6 +3871,82 @@ drm_dp_mst_atomic_check_topology_state(struct drm_dp_mst_topology_mgr *mgr,
 	return 0;
 }
 
+/**
+ * drm_dp_mst_atomic_enable_dsc - Set DSC Enable Flag to On/Off
+ * @state: Pointer to the new &struct drm_dp_mst_topology_state
+ * @pointer: Pointer to the affected MST Port
+ * @pbn: Newly recalculated bw required for link with DSC enabled
+ * @enable: Boolean flag enabling or disabling DSC on the port
+ *
+ * This function enables DSC on the given Port
+ * by recalculating its vcpi from pbn provided
+ * and sets dsc_enable flag to keep track of which
+ * ports have DSC enabled
+ *
+ * See also:
+ * drm_dp_helper_update_vcpi_slots_for_dsc()
+ */
+int drm_dp_mst_atomic_enable_dsc(struct drm_atomic_state *state,
+				 struct drm_dp_mst_port *port,
+				 int pbn,
+				 bool enable)
+{
+	struct drm_dp_mst_topology_state *mst_state;
+	struct drm_dp_vcpi_allocation *pos;
+	struct drm_connector_state *conn_state;
+	struct drm_crtc *crtc;
+	struct drm_crtc_state *crtc_state;
+	bool found = false;
+	int vcpi = 0;
+
+	mst_state = drm_atomic_get_mst_topology_state(state, port->mgr);
+
+	if (IS_ERR(mst_state))
+		return PTR_ERR(mst_state);
+
+	list_for_each_entry(pos, &mst_state->vcpis, next) {
+		if (pos->port == port) {
+			found = true;
+			break;
+		}
+	}
+
+	if (!found)
+		return -EINVAL;
+
+	if (pos->dsc_enabled == enable)
+		return 0;
+
+	if (enable) {
+		vcpi = drm_dp_atomic_find_vcpi_slots(state, port->mgr, port, pbn);
+
+		if (vcpi < 0)
+			return -EINVAL;
+	}
+
+	pos->dsc_enabled = enable;
+
+	conn_state = drm_atomic_get_connector_state(mst_state->base.state,
+						    port->connector);
+
+	if (IS_ERR(conn_state))
+		return PTR_ERR(conn_state);
+
+	crtc = conn_state->crtc;
+
+	if (!crtc)
+		return -EINVAL;
+
+	crtc_state = drm_atomic_get_crtc_state(mst_state->base.state, crtc);
+
+	if (IS_ERR(crtc_state))
+		return PTR_ERR(crtc_state);
+
+	crtc_state->mode_changed = true;
+
+	return vcpi;
+}
+EXPORT_SYMBOL(drm_dp_mst_atomic_enable_dsc);
 /**
  * drm_dp_mst_atomic_check - Check that the new state of an MST topology in an
  * atomic update is valid
diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h
index 4cf738545dfb..0a9aed1c00ff 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_enabled;
 	struct list_head next;
 };
 
@@ -662,6 +663,10 @@ 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_mst_atomic_enable_dsc(struct drm_atomic_state *state,
+				 struct drm_dp_mst_port *port,
+				 int pbn,
+				 bool enable);
 int __must_check
 drm_dp_atomic_release_vcpi_slots(struct drm_atomic_state *state,
 				 struct drm_dp_mst_topology_mgr *mgr,
-- 
2.17.1