[PATCH v7 4/4] drm/dp: Track MST link bandwidth

[Dhinakaran Pandiyan]

From: "Pandiyan, Dhinakaran" <dhinakaran.pandiyan at intel.com>

Use the added helpers to track MST link bandwidth for atomic modesets.
Link bw is acquired in the ->atomic_check() phase when CRTCs are being
enabled with drm_atomic_find_vcpi_slots() instead of drm_find_vcpi_slots().
Similarly, link bw is released during ->atomic_check() with the connector
helper callback ->atomic_release() when CRTCs are disabled.

v5: Implement connector->atomic_check() in place of atomic_release()
v4: Return an int from intel_dp_mst_atomic_release() (Maarten)
v3:
 Handled the case where ->atomic_release() is called more than once
 during an atomic_check() for the same state.
v2:
 Squashed atomic_release() implementation and caller (Daniel)
 Fixed logic for connector-crtc switching case (Daniel)
 Fixed logic for suspend-resume case.

Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Cc: Archit Taneja <architt at codeaurora.org>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Harry Wentland <Harry.wentland at amd.com>
Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
---
 drivers/gpu/drm/i915/intel_dp_mst.c | 57 +++++++++++++++++++++++++++++++++----
 1 file changed, 51 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
index 5af22a7..20c557c 100644
--- a/drivers/gpu/drm/i915/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/intel_dp_mst.c
@@ -39,9 +39,9 @@ static bool intel_dp_mst_compute_config(struct intel_encoder *encoder,
 	struct intel_dp *intel_dp = &intel_dig_port->dp;
 	struct intel_connector *connector =
 		to_intel_connector(conn_state->connector);
-	struct drm_atomic_state *state;
+	struct drm_atomic_state *state = pipe_config->base.state;
 	int bpp;
-	int lane_count, slots;
+	int lane_count, slots = 0;
 	const struct drm_display_mode *adjusted_mode = &pipe_config->base.adjusted_mode;
 	int mst_pbn;
 
@@ -63,24 +63,68 @@ static bool intel_dp_mst_compute_config(struct intel_encoder *encoder,
 	pipe_config->pipe_bpp = bpp;
 	pipe_config->port_clock = intel_dp_max_link_rate(intel_dp);
 
-	state = pipe_config->base.state;
-
 	if (drm_dp_mst_port_has_audio(&intel_dp->mst_mgr, connector->port))
 		pipe_config->has_audio = true;
-	mst_pbn = drm_dp_calc_pbn_mode(adjusted_mode->crtc_clock, bpp);
 
+	mst_pbn = drm_dp_calc_pbn_mode(adjusted_mode->crtc_clock, bpp);
 	pipe_config->pbn = mst_pbn;
-	slots = drm_dp_find_vcpi_slots(&intel_dp->mst_mgr, mst_pbn);
 
 	intel_link_compute_m_n(bpp, lane_count,
 			       adjusted_mode->crtc_clock,
 			       pipe_config->port_clock,
 			       &pipe_config->dp_m_n);
 
+	if (pipe_config->base.active) {
+		slots = drm_dp_atomic_find_vcpi_slots(state, &intel_dp->mst_mgr,
+					      connector->port, mst_pbn);
+		if (slots < 0) {
+			DRM_DEBUG_KMS("failed finding vcpi slots:%d\n", slots);
+			return false;
+		}
+	}
 	pipe_config->dp_m_n.tu = slots;
 
 	return true;
+}
 
+static inline bool release_resources(struct drm_crtc_state *crtc_state)
+{
+	return (crtc_state->connectors_changed ||
+		crtc_state->mode_changed ||
+		(crtc_state->active_changed && !crtc_state->active));
+}
+
+static int intel_dp_mst_atomic_check(struct drm_connector *connector,
+		struct drm_connector_state *new_conn_state)
+{
+	struct drm_atomic_state *state = new_conn_state->state;
+	struct drm_connector_state *old_conn_state;
+	struct drm_crtc *old_crtc;
+	struct drm_crtc_state *crtc_state;
+	int slots, ret = 0;
+
+	old_conn_state = drm_atomic_get_old_connector_state(state, connector);
+	old_crtc = old_conn_state->crtc;
+	if (!old_crtc)
+		return 0;
+
+	crtc_state = drm_atomic_get_new_crtc_state(state, old_crtc);
+	slots = to_intel_crtc_state(crtc_state)->dp_m_n.tu;
+
+	if (release_resources(crtc_state) && slots > 0) {
+		struct drm_dp_mst_topology_mgr *mgr;
+		struct drm_encoder *old_encoder;
+
+		old_encoder = old_conn_state->best_encoder;
+		mgr = &enc_to_mst(old_encoder)->primary->dp.mst_mgr;
+
+		ret = drm_dp_atomic_release_vcpi_slots(state, mgr, slots);
+		if (ret)
+			DRM_DEBUG_KMS("failed releasing %d vcpi slots:%d\n", slots, ret);
+		else
+			to_intel_crtc_state(crtc_state)->dp_m_n.tu = 0;
+	}
+	return ret;
 }
 
 static void intel_mst_disable_dp(struct intel_encoder *encoder,
@@ -378,6 +422,7 @@ static const struct drm_connector_helper_funcs intel_dp_mst_connector_helper_fun
 	.mode_valid = intel_dp_mst_mode_valid,
 	.atomic_best_encoder = intel_mst_atomic_best_encoder,
 	.best_encoder = intel_mst_best_encoder,
+	.atomic_check = intel_dp_mst_atomic_check,
 };
 
 static void intel_dp_mst_encoder_destroy(struct drm_encoder *encoder)
-- 
2.7.4